Can't get JF to find my movies

[Lost Newb]

Sorry, but I can't get Jellyfin to find the movies and add them to my server.  First of all, I am completely brand new to Ubuntu (I'm not even that great at Mac or Windows to be honest).  I just installed Ubuntu 20.04 and then Jellyfin on my old Compaq Presario laptop.  EVERYTHING has been a struggle due to my ignorance and I feel like I've been beating my head against a wall.

My media are movies ripped with MakeMKV and converted to mp4 files with Handbrake.  As a test, I put a movie on a thumb drive but can't get JF to "find" it.  At first I thought it was a permissions issue, then a "path" issue, then a naming issue but now I'm not sure. 

-My thumbdrive's name is "movies"
-I read that I shouldn't put the movies directly into a main folder, so I created a main folder named "movies"
- within my main "movies" folder, I put a file named "Sherlock Holmes (2009) [tt0988045].mp4".  So I think my name is good.

As far as my "path" that I enter into the "folders" bar in JF, that's been problem at times.  I was getting "path not found" errors.  What I am doing is going through the "files" app in Ubuntu, navigating to my movie's mp4 file, hit "ctrl + L" and the path appears in the bar at the top of the page.  I put and paste that into the "folders" bar in JF .  That path looks like this "/mnt/usb-General_UDisk_2409181453306224934310-0:0-part1/movies."  Libraries accepts this path but when I "scan all libraries", the progress bar flashes for a split second, but it appears my file is not found. 

As far as permissions, when I click on my USB drive named "movies" in Ubuntu and look at properties, the drive owner is listed as "root" and access is listed as "create and delete."  Not sure if that's a problem or not.

Hopefully it's something obvious.  If you have any recommendation or thoughts, please be explicit and assume that I know very little because that's the case.  Thank you very much.

[TheDreadPirate]

Additional permission restrictions are usually applied to USB drives that are almost certainly preventing Jellyfin from accessing it.

On a command prompt and run these commands. Unrelated, Jellyfin does not use IMDB for any metadata. TMDB is the default provider.

Also, replace "yourUser" with your actual Ubuntu username.

Code:

cd /media
sudo mkdir -p "Movies/Sherlock Holmes (2009) [tmdbid-10528]"
sudo chown -R yourUser:jellyfin Movies

Now copy the movie on your thumb drive to this folder.

Code:

sudo chown -R yourUser:jellyfin Movies
sudo chmod -R g+rx Movies

Add this folder to Jellyfin and scan.

[Lost Newb]

Thank you very much.  So on my thumb drive I created a folder called "jellyfin Movies" and in that folder put my renamed movie (Sherlock Holmes (2009) [tmdbid-10528].mp4).

Under Libraries, the path I used (ctrl+L) to add to "folder" was this "/mnt/usb-General_UDisk_2409181453306224934310-0:0-part1/jellyfin Movies"  When I "scan all libraries", I still get a split second progress bar flash but nothing is found.

Believing that somehow I'm not able to get it to read an external drive, but perhaps a file on my computer's SSD drive would be different, I put another .mp4 file into the native "videos" folder in Ubuntu. African Queen (1952) [tmdbid-488].mp4.  I obtained the path  /home/<my name>/Videos  by pressing "ctrl+L" but when I scan all libraries, I get the dreaded "The path could not be found. Please ensure the path is valid and try again."  Under permissions, I am the "owner" and "group" of this file and have read and write access of this file. 

At least in the second try, it seems permission is not the problem.  Any other thoughts?  Does it seem like my "paths" are correct?  Thanks.