I am thinking about purchasing a Galaxy Tab A 10.1 2019. I mainly want to transfer scores of pdf / books on my Desktop, to the tablet so that I may read them at a location other than my home office desk. But it is unclear to me how, for a Galaxy Tab A 10.1 2019,  I can create various folders (e.g., "History_Ancient" -- without the quotation marks) *within* Internal Storage / My Files from the following instructions given on the Samsung website: "1. Navigate to My Files, and then tap Internal storage. 2. Select your desired category. You can choose between Images, Videos, Audio (music files), Documents, Downloads, or Installation files. 3. If needed, select the folder that contains your desired files (i.e. Camera, Screenshots, etc.). Touch and hold the file(s) or folder(s) you want to move. 4. Tap Copy to create a copy of the files in a different storage area. Or, tap Move to completely remove the file and move it to a new location. 5. Next, navigate to and select your desired destination: 6. Internal storage: Move the file(s) or folder(s) to a different location within the same internal storage. 7. SD card: If you have a microSD card inserted, tap SD card, and then select the destination location. Please be aware that apps cannot be moved to the SD card using My Files. You will need to use another method. 8. Once you've found where you want to put the file, tap Move here or tap Copy here."

The Samsung website does not make clear how to *create* the "new location" / folder (items #4-8) -- for example, "Literary Criticism_General" -- in which to place various pdf / book files (scores of pdf books in SEVERAL categories on my Desktop).

I made the mistake of purchasing an Amazon Fire 10, since reviews said that pdf books could be transferred to it. What the reviews failed to mention is that the Fire OS does *not* allow books transferred by USB cable (which has to be done if they exceed the 20 GB limit of my gmail, in the Amazon email system of transferring) to be categorized (put in folders -- "Collections" in the Amazon OS system). The Galaxy Tab A 10.1, 2019, is reportedly running Android 9.0 / Pie.

I would suggest that you use something like OneDrive to put the documents on your tablet.  With OneDrive you can create the folder structure you desire on your computer and it will automatically be replicated on your tablet. The folders and files will be uploaded to the cloud from your computer and then downloaded from the cloud to your tablet in the background with no intervention from you.  If you add a new document to your computer, it will automatically be synced to your tablet within minutes.  You can create a free Basic OneDrive account with 5GB of storage but if you need it you can purchase additional storage.

You will need to setup OneDrive on your computer and install the OneDrive app on your tablet.

There are other similar solutions you could look into as well such as DropBox and Google Docs.Thanks for the SUGGESTION. Does "OneDrive" itself do this automatic syncing of the Desktop to the tablet? Isn't there an easier way to do PDF / book folders (or subfolders) in Android 9.0 Pie? I ask because I've seen references to Android 9.0 Pie being very comparable to Windows Explorer, and I'm very familiar with Windows Explorer . . . Is it possible that the OneDrive SOLUTION will work on the unfortunately-modified Fire OS?You can search on Amazon for apps for the Fire 10.  I did such a search and found there is a OneDrive app for the Fire OS.

I'm not sure why you think it would be easier to hook up a cable to a tablet in order to copy files over to it as I think the OneDrive solution is hands down easier..  Yes, OneDrive automatically syncs anything you place in it's subfolders to/from your computer.  Since you are familiar with Windows File Explorer, it would be a piece of cake to setup OneDrive with the folder hierarchy you wish and then OneDrive would SYNC it to your tablet.Thanks to the respondents to my questions. Attached are photos of most of my folders and subfolders of pdf books. The total of all these is 16.09 GB. As a newbie in some respects (though I go all the way back to the Vic-20 and Commodore 64, and *tape drive storage* -- on actual cassette audiotape), I don't understand the mechanics of sync-ing. If I set up the folders and subfolders in OneDrive or Dropbox, does this sync-ing take place over Wifi?

The Amazon Fire tablet helps suggest why Blue Origin is so far behind SpaceX. The Amazon Fire OS is notorious on Internet complaints for not supporting OneDrive, Dropbox, folders, and subfolders -- unlike Android 9.0 / Pie. (I didn't realize this when I read reports that pdf files could be "transferred" to the Fire tablet via email or usb cable). The SPECIAL file system in the Fire OS has only provisions for "Collections," which do not appear as folders or subfolders in file management software; only pdf files/ books less than 20 megs can be "transferred" by most email services, which then can connect with the special Kindle / Fire Amazon server to connect to the Fire and place items in a "Collection." Any file "transferred" by USB cable -- a problem *not* reported on the Internet -- cannot be placed in a "Collection," which I finally discovered after more than an hour and 3 (!) Kindle / Fire specialists, each passing the buck (actually Rupee) to the next specialist. The Amazon Fire tablet -- as opposed, I think, to either the budget tablets from Lenovo or Samsung -- is set up, like other Amazon products, to market Amazon products (especially Kindle books). There are Internet complaints about the lack of depth in the Fire / Kindle help specialists, as well, which are justified in my experience.When you plug a tablet or phone into a windows PC  a menu will come up on the device asking how the device will be handled by the PC. See attached picture

If you select file transfer the tablet will appear to the computer as a drive so you can do all the things which you can do with a Hard drive. Like Copy and delete files or directories.
The 32 gb storage in the galaxy is enough for txt files. If you want to store moves' then a expansion sim may be necessary. If you do get expansion memory then make it a separate drive  not as an addition to the memory in the tablet.

This should also be the same on your kindle fire
I found this on the web https://www.amazon.com/gp/help/customer/display.html?nodeId=201730100

PS I like what you are reading.