You can use this resource pack in any modpack (including ones you publish) and modify it however you want - just don't redistribute it without my permission.
In fact, I'd prefer if someone with any sort of texturing talent could make their own add-on for all the versions this supports (or at least 1.18+) since I'm barely capable of making a square that doesn't look like shit lol.
For modpacks: Credit is not required, but is appreciated (as I spent far too long making this lol).
For resource packs: Credit is required if you use some assets from this in your own resource pack (e.g. using my UI templates to make development easier)
If you want to contribute, feel free to do so. Simply open a pull request (or message me on discord) and let me know what you want to add. I'll add you to the credits, and can add you to the CurseForge and/or Modrinth pages as well.