These are the maps from the 2nd edition of the 90MC here in Trackmania 2020.
It's a competition where you're given a theme and tasked with building a map within 90 minutes.
The theme for this 1st edition was:
Get Blocked!
Every block in the route has to be different to the blocks immediately connected to it (so right before, after and next to it). So you are allowed to use the same type of block multiple times in your track, you just cannot use them "in a row".
The host for this edition was Sky.
More info here:
https://trackmania.exchange/threads/167?postid=10642