

Four spaces before the line you want to codify :)
e.g.
UUID=“your uuid” /mnt/external exfat defaults,uid=1000,gid=“your group id”,umask=002,nofail 0 0
vs non-formatted
UUID=“your uuid” /mnt/external exfat defaults,uid=1000,gid=“your group id”,umask=002,nofail 0 0



Feels like this should have already been resolved with standard Linux permissions, any user on your system should be able to read/traverse that folder and files with the r-x permission on world.
From your earlier comment one of the parent directories is listing with “+” permission so it sounds like you are using extra permissions outside of the standard Linux, probably ACL permissions. I haven’t worked with ACL permissions on Linux enough to offer much advice but what you may want to do is run something like getfacl d64ea996-98aa-4eef-8a93-0a2ba2246f0f as well as run it on one of your media files, that might give you some clues on what the ACL permissions look like.
Also - I’m assuming you already did this - but if you didn’t already make sure your jellyfin service is actually launching with the expected user and user group. Based on your setup you may want to be sure the “jellyfin” Linux user is added to the “video” user group, and then make sure that’s what is being referenced in jellyfin.service.conf (by default is usually in /etc/systemd/system/jellyfin.service.d). If you edit that file be sure to stop the jellyfin service first and then restart it after editing e.g. “systemctl stop jellyfin” and “systemctl start jellyfin”.
Only other thing I can think of is that maybe there’s something wrong with the way your system is mounting the drive and folder. Since you seem to be using the autogenerated UUID for the mounted folder name (d64ea996-98aa-4eef-8a93-0a2ba2246f0f) maybe it’s better to edit fstab yourself and set up your mount as something more permanent with a normal name, and also double-check the permissions everything is mounting as.