The first thing you will be met with when you open the customer app is the login screen.
The credentials used here are issued by your service provider.
You can contact them to get a new set of credentials.
There will soon be a self service interface for administrative customer accounts, for adding and managing users for your company, in the web customer portal.
(There is a large scale migration of the users from the old customer app's user list planned for the latter part of Q1 2023.
Until that migration is complete users have to be manually added by their service provider.)