After upgrading to 2021.2.0f1 Plastic SCM is gone, errors are all over the place

It’s very likely that some of your students’ organizations were already migrated during the automated process that’s currently ongoing for all Collab projects. They can know for sure if their orgs were migrated for them if they received an email from Plastic SCM saying that the migration was complete.

I’m very happy to hear that the test worked for one of your students and I hope it works for the rest! If the Collaborate icon is still visible then I’d ask them to double check that Collaborate was disabled in the Project Settings.

Happy to help and don’t hesitate to reach out if you or your students run into any other issues.

How do you install Version Control package?
After migrating my project from Collaboration to Plastic SCM, I have removed Version Control from Package Manager to avoid some collab compilation errors. Now I can’t find a way to install Plastic SCM or Version Control back. It’s not available in asset store. How can I install these plugins?

Unity version 2020.3.8f1.417 Personal
EDIT: I have also found this in other topic:
“I’m afraid that your version of 2020.3 is not supported by the Version Control package. You’ll need to upgrade to Unity 2020.3.20f1 or later.”
The problem is Unity says I have the most recent version. How do I update?
I tried “Help > Check for updates” and I get
“The Unity Editor is up to date. Currently installed version is 2020.3.8f1”

EDIT: answer is here: Help Wanted - What version of Version Control works on 2020.3.8f1? - Unity Forum