Buildhub does not have permissions to create subscription

TL'DR: Make sure BuildHub can create subscription. A quick and easy fix is to give BuildHub Pub/Sub Editor role. Or you can skip this step and create the topic manually. Doing it this way will require less permissions.

To start receiving notification, BuildHub need to subscribe to cloud-build topic. The first step is to create a new subscription for our service to connect to. We can do it for you if have sufficient permission: