I don't know if minecraft trail downloaded from microsoft has a copyright to speedrun, can it speedrun? hmm...

Can anyone give me an answer?

Yeah, any game can be added to this site regardless of copyright. As I haven't heard of any major game developers compain about this.

And is Minecraft Trail already added as a game on the site?

If so, then of course you can speedrun it as it's already on it and that other people have.

If not, then were you asking this question to add the game to the site yourself?

Also, I can't find a game that's called that.

They probably mean "Minecraft Trial". Found at least 1 mobile app with that name.