02 Servers
server1 and jserver.
Emby is server1. Jellyfin is jserver, checked on its own — not as a side effect of Emby. Use the address you already open, and delete /web from the end. The API key is in that server's dashboard.
server1
Emby
Primary playback. Login starts here.
jserver
Jellyfin
Jellyfin dashboard, then Advanced, then API Keys. A user and password are optional and only check that a person can sign in.