Trial MEP Pro Plus version 20.0.1.73 running on Windows 10 has no Collages Basic button under Design elements in the Templates tab! According to https://www.magix.com/us/video-editor/how-to-make-a-video-collage/ there should be one next to the Picture in Picture button.
I see no "Extra Content" in the help menu. I do see he following which I clicked in the order written: Download My Store Content Activate Content Packs
I see nothing new in my Downloads folder. I closed the program,started again, created a new project, brought in my clips but I still have the same problem. Collages Basic is not there.