I'm trying to create new items, spells, sub-classes, etc on DnD Beyond; but it's not a very user friendly interface. I can't find any compendium or database that has a list of all the macros that I would https://vidmate****/ need to type and format so that they function properly.

Does anyone here have any experience https://mobdro****/ with this, and could help me out?

The homebrew forum has a bunch of pinned threads with useful information:
https://www.dndbeyond.com/forums/dungeons-dragons-discussion/homebrew-house-rules

Stormknight made some videos that are a more in-depth walk through:
https://www.dndbeyond.com/forums/dungeons-dragons-discussion/homebrew-house-rules/3625-everything-you-need-to-know-about-homebrew
They are a little out of date now but it should get you started.

If you have a specific question on how to implement something that is the forum to ask in as well.

Yes, I have extensive experience with the homebrew creator. I’m actually the author of one of those pinned threads that Houligan mentioned, the FAQ, which you may find helpful: (https://www.dndbeyond.com/forums/dungeons-dragons-discussion/homebrew-house-rules/131411-a-homebrewers-how-to-faq). If you need specific help, just post in the Homebrew forum and either I or someone else will help out whenever we can.