Scratch wiki wrote:

Multiple Animator Projects (commonly known as MAPs) are collaborative projects by numerous Scratchers that each contribute a short animation to the project.

MAPs are usually set to music or audio clips which have been sliced into shorter segments, although some MAPs do not have background audio. Each project member is responsible for animating their assigned part. Once each Scratcher has completed their part(s), the creator of the original MAP puts all parts into a single project.

I plan to make a MAP soon but in the past every time I've done so, they've all failed miserably. How can I make a good MAP and have lots of people join it?

Well, when reading that article-like text, I immediantly thought of a way. First, make a studio and invite people to it, then allow people to add their part of the MAP project. It is recommended to add a list of availiable MAP parts to do or a Scratch project guiding through it, but this is optional. Next, when all the MAP projects are completed and gathered, combine all the animations together to make the project. Edit it if needed or wished and you would be done with the project! Finally, it is recommended to share this to the public and maybe back in the studio but this is also optional.

I’ll join as long as I can make stuff similar to what is below