Customer&Business Manager is installed with Plesk in a VPS hosting subscription. Access to the Customer&Business Manager Control Panel from Plesk is denied if you log in to the Plesk Control Panel using the Plesk autologin link in the Parallels Operations Automation (POA) customer Control Panel. If you click on the Plesk autologin link, you will be successfully logged in to the Plesk Control Panel, but if you switch to the Customer&Business Manager, you will be prompted for credentials.
SSO authorization is used when you access Customer&Business Manager. SSO authorization works if you use direct login to access the Plesk Control Panel from the browser, instead of the autologin.
To be able to access the Customer&Business Manager, correct login credentials must be entered. Use admin user name and admin password to log in into the Customer&Business Manager Control Panel.
If you do not know the login credentials for admin user, you can set a new password via the POA customer Control Panel:
POA > select PVC container subscription with Plesk > VPS > Plesk > click Change Admin Password button > set a new password for admin user.
Use the new password to log in to Customer&Business Manager.