I recently found PlatinumQuest and it has a section with all of the MBU levels. Would this count as an emulator, and are the runs I do on it allowed?

Link: https://marbleblast.com/index.php/downloads/pq

Since it's a different game, it would belong in the PlatinumQuest boards. They don't seem to have an Ultra category at the moment, but you can suggest it to them. https://www.speedrun.com/PlatinumQuest