This is NOT legal advice. You’re pretty much substituting yourself for the library. So, all the business stuff the library would do, you will have to do. Aside from the creative aspects, you will need to give the editor info/docs showing that you have full rights to the music. If you created/produced/performed everything, it will be easy. If you hired musicians, singers, etc., you will need to get waiver/assignments from them. The editor may have forms that you can use as a go-by.
There are websites that go through these issues. In your search add “one stop” and “easy clear” to the search.
Look at setting up a publishing company entity and set up a publishing account with your PRO. You can do it without, but It will make you look more professional.