Receiving secured Roku Pay push notifications

We are utilizing the Roku's push notification feature. Upon receiving a notification on our server, is there a specific deadline or time limit for responding back to the Roku?

We just skimmed through the below documentation 

https://developer.roku.com/docs/developer-program/roku-pay/implementation/push-notifications-jwt.md

In this doc we could only see the responses that roku is expecting us to send back but no any information regarding acknowledgment time for a request