If you’re running PhotoPrism through Docker (see Deploy PhotoPrism in a Container), you can add additional users from the photoprism CLI inside the container rather than through the web UI:

docker compose exec photoprism photoprism users add -p YOURPASSWORD -n YOURNAME -m YOUREMAILADDRESS YOURUSERNAME

Replace YOURPASSWORD, YOURNAME, YOUREMAILADDRESS, and YOURUSERNAME with the new user’s actual details.