There are two methods if you want to do a polling wait in the same/single scenario.
Method 1 — difficulty level: Easy
The simplest solution would be to use a Sleep module to wait out 5 minutes (or the longest period that the external service takes).
You could even use more than one, if you have a Make subscription (free tier max 5 minutes per scenario run).
Method 2 — difficulty level: ???
This other method allows you to check multiple times at shorter intervals, because you “throw” an error to break from the repeater and end the scenario when successful/completed.
The secret is in the success check filter, the error handler, and the commit directive.