Proper App Store Connect user permissions to generate or renew push notification certificates

Since merging account rights on the Developer Portal and App Store Connect you may have lost the ability to add new app ids and to generate / renew push notification certificates.

As per this Stackoverflow answer, you have to make sure that you set up user permissions as shown below (Developer, App Manager, and Access to Certs and Profiles)...

Important details:

• You will only be able to give access to other users if you have a orgnization account. For personal accounts the account owner needs to perform any certificate related functions.
  
• You can only grant App Manager access if you have Admin access; without this it will be greyed out