jellyfin unable to access files on external and internal storage

[mhkb]

Unfortunately, I can't get enough feedback and information and you aren't able to do the basics.

This is like asking a blind person to drive while I give them directions over the phone. 

Even more user friendly Linux distros require a level of knowledge you don't have yet.  If you're more familiar with Windows, I'd suggest using that as a server.  Obviously that is not possible on a RPi.  But a cheap, used PC or laptop can be used as a server.  I'm not sure if that is an option for you.

atleast help me get the permission of usb drive.
will use the sd card for server.
somehow reverting the ACL command you mentioned.