GMB API - Working with PubSub to get real time reviews notification

Question

I have integrated GMB API in our platform and working with PubSub to get realtime reviews notification.
For which i have already done the following steps:

1. Created topic on google PubSub cloud.
2. Created its subscription of push type with a valid https url.
3. Updated Google Business Account Notification with the topic created in step one with all kind of notification type.

Problem:

1. After successfully completing the 3 steps above, Google is still not pushing the reviews data to my server when I go to My Business API and edit the review.
2. Can I create a single topic for all users and use a single subscription of application, so when users authorize their My Business API with our platform we just have to link those businesses with that single topic to get their notification?

This is what i get from google's documentation.
Any respond is highly appreciated.

Thank you :)

Answer 1

Did you give Publish rights to the mybusiness-api-pubsub@system.gserviceaccount.com email address. Since it works for me with the above steps. Though the messages are bit delayed.