Bill Management External users vs internal users

Inorder to enable Billing Managment for external users, i have updated existing contact on the customer account to my personal gmail id . Then i tried to register user under BillManagement registartion but i am not able to see the contact email that i updated for selection.

I have tried creating user details(gmail) with the above contact under security console →users and have run LDAP scheduled process to synchronize. I didn't recieve any email with link to my gmail

Also, when i try logging in with internal user email, i can't see Account overview or Transaction Screen.

Bill Management icon is not displayed on the homescreen even when enabled via Tools-Structure→Billing Management