To invite the app builder account on Google Play, please ask your client to follow these steps:
1. Login to your Google Play developer account at https://play.google.com/apps/publish.
2. Go to the settings page and choose ‘Users and permissions’. Then click ‘Invite new user’ Inviting the App Builder Account on Google Play
3. Enter the email address ‘appbuilder.submissions@gmail.com’, select Account Permissions then ‘Admin (all permissions)’ and click ‘Send Invitation’.