Hi folks,
Multiple players have reported an issue where downloads of Forza Horizon 3 on Windows 10 continually restart, and are not yet completed. For these users, we have received two workarounds that may possibly address the issue:
1) Installing the game to a non-system drive
2) Or wait until the game is fully released in your region, cancel the download, then restart the download.
We will continue to investigate this issue and will update the community with new information when it is available.
Thanks,
Brian