As Giacomo and Gabriele suggested you can try to reset the password by editing the webtop5 postgreSQL database.
You can do it from the command line:
su - postgres
psql webtop5
UPDATE "core"."local_vault" SET password_type='PLAIN', password='admin' WHERE user_id='admin';
\q
exit
After that, try to login with admin/admin, and if it works use webtop interface to set a new admin password as soon as possible.
Nice, thanks for checking the code. I bet you’ve found a bug.