How can I create photo albums? I still have lots of old photos that I want to add to plex. Currently they are simply organized in folders, but plex recognizes them as a media library instead of an album
Plex’s photo libraries follow your folder structure exactly, so if you have them in folders, just make sure Plex is in ‘Library’ view.
If you want to pick and choose photos to show as an ‘album,’ you can create playlists, either from the overflow menu on each individual photo:

Or after selecting multiple photos, from the Playlist menu at the top:

If you create a playlist, it will be accessible from within the Photo library via the ‘Playlists’ tab:
Or on the Playlists page (Photos tab):