You have one account. The same email address and password work on both sites:
Server panel — ai.gameteam.io. Start and stop your server, edit files and settings, install mods, take backups, read the console.
Billing — bill.gameteam.io. Invoices, upgrades, cancellations and tickets.
There is no separate control-panel password to look for, and none is sent to you by email. If you can sign in to billing, you can sign in to the panel with exactly the same details.
If the password is not working, reset it from the billing login page — the new password applies to both sites.
If you need help with this, please submit a ticket.