@ebecker1 there is no easy way to connect to the database from outside. However I am not sure at all if your approach here is correct. I would assume the app has better ways to import data besides tinkering with the underlying database as that seems quite the risky operation and might break the app itself.
@nebulon switched to chromium. It works. Back to firefox I've recognized the following: switch status green = no signup link, switch status grey = signup link.
And after looking at the full description, it makes sense.
Enabling the "Allow creating new accounts" signup restriction means: it is not allowed. It's a usability issue on my end. Sorry for the interruption