You have to play all challenges in one go.
In which order doesn't matter so start from the top.
Or like me with challenge 13. This one is the one I had the most problems with.
Loading screens do count towards the 45 mins.
Playlist with all challenges in seperate videos can be found here:https://www.youtube.com/playlist?list=PLx71cHij1Wfy2wQ-L2gjN...