From this issue: https://github.com/xamarin/test-cloud-operations/issues/620
Slack has confirmed that the app requests Play Services and bubbles up the dialog to the system. They were hoping to get the Play Services installed as needed. The device of particular importance is the OnePlus.
I was able to glean from Slack that the Play Services are necessary for user notifications. Seeing as this is an automated test notifications would be a nice bonus but not game breaking. Slack could potentially dismiss the dialog via automation.
|Device Model Name||OnePlus One|
|Operating System Version|