ISPmgr and billmgr authorization not working?

Question

Billing systems

Hello. Please tell me:
I installed billmgr on my server, configured the address of the control panel according to the bill manager documentation: https://docs.ispsystem.ru/billmanager/pervonachal-...
I have all the configurations as in the documentation. Everything is installed, but authorization works. When I enter correct data from root, the authorization page simply reloads, and when I enter incorrect data, it says that the data is incorrect. There are guesses, this is due to SSL, but I do not know how to fix it.