Open Registry Editor: Win+R | regedit
Navigate to the registry path: HKLM\SOFTWARE\WOW6432Node\Microsoft\Windows NT\CurrentVersion
Temporarily modify these 3 registry keys:
- CurrentBuild set value to 17134 (instead of 17763)
- CurrentBuildNumber set value to 17134 (instead of 17763)
- ReleaseId set value to 1803 (instead of 1809)
Restore initial values of the 3 keys (step 3)
Restart PC and complete setup of iCloud