I am not seeing any error at all. The login screen (from my app) does appear but when i used user/pass from postgresql db, it does nothing.
Here is the link for the same app on a raspberry pi behind NAT that works just fine: https://up.userpassmanager.com
This mojo app can be accessed in multiple ways: http://userpassmanager.com:33333 or https://u.userpassmanager.com or https://userpassmanager.com:33334. I hope that clears the hostname confusion. (u.userpassmanager.com is just proxy to userpassmanager.com:33333)
I am also able to login to virtualmin as upmanager and edit/manage postgresql database upmanager; But not in my Mojolicious app.
I think it has much to do with user/database/table/host permissions with PostgreSQL which you also alluded to. I hope someone with deeper PostgreSQL knowledge would help me with it.
I am asking it here because I am trying it on Centos8 with Virtualmin ( same source code works just fine in the Raspberry Pi).