@Christian W, Thanks for posting in Q&A.
For the error code 0x81036502, it means time out when install apps. To find out which app is the affected one, it needs to review logs. To troubleshoot such issue, open case is suggested. Here is a link with the steps to open case:
https://learn.microsoft.com/en-us/mem/get-support
As another option, you can unassign the apps to these devices to make the Autopilot enrollment complete. Then we can check if the device status can be OK. After the device status is OK. Then we can re-assign the apps to one device one by one to find the affected app and troubleshoot.
Hope it can help.
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