See my prior post. RequiresMountFor does not go in a separate .conf file. It goes in jellyfin.server. I provided you with a direct copy and paste example in the post.
Jellyfin 10.10.7 (Docker)
Ubuntu 24.04.2 LTS w/HWE
Intel i3 12100
Intel Arc A380
OS drive - SK Hynix P41 1TB
Storage
4x WD Red Pro 6TB CMR in RAIDZ1