Error CS0246 and Error CS0115 when upgrading Unity Project

Hello,

I work with a team that relies on using Unity Collab, and lately when I upgrade my version to the latest version of Unity to the one that they use, I'm the only person who gets these errors. I have reset my packages to default, reinstalled them, as well as deleted the collaboration file to then re-download the fresh project. Nothing I do seems to work, and when I upgrade I also lose the ability to use the Unity Collaboration tool within that specific project.

I'm not sure what else there is to try, and I need to be able to upgrade Unity versions to continue to contribute to projects.

Any help would be greatly appreciated!