The folders that AE creates are for your User Libraries, User Presets, and saved Video Libraries. The User Presets (Adobe) is only an alias so no files are actually stored there. I have created an Alias for my Custom Presets that points to a Dropbox folder because I have almost 300 of them and I use at least one of them in almost every project I do and I want to have access to them even when I am working on somebody else's computer.
I don't know any easy way to change the folder, just like there is no easy way to change the Library folders that Adobe and just about every other app that is more complicated than Notepad creates to manage all the assets. The Custom Presets folder I have in Dropbox is nearly 7 MB, but the entire Documents/After Effects 2020 folder is only 33KB. That's the magic of aliases.