I just tried using the Alarm Clock extension with RopieeeXL 2.536 beta and am having trouble getting it to work after a reboot of the Ropieee Pi.
As an experiment, I set an alarm for +5 minutes and then rebooted the pi. When I looked at the Alarm Extension settings on my Mac after the reboot, the date of the alarm was the previous day (Sunday rather than today, i.e. Monday).
As an experiment, I tried installing the Alarm extension Docker container on another pi running Buster and made the same alarm. After rebooting that Pi, the date was set correctly and the alarm functioned properly.
I am based in the UK if it makes a difference.