The shuffle behavior is intended functionality of the Alarm Clock extension. I choose to always shuffle a playlist because I assumed the selected playlist to be pretty static and wanted to avoid waking up every day with the same song, but your use case is clearly different.
I previously described my thought process here:
There I also described that album selection is not provided because it would be a terrible experience when dealing with thousands of albums.
Back to the shuffling of playlists, the Roon API provides the functionality to play a playlist in order but that requires an update of the extension. I might include this in the next release, but no ETA.