I downloaded my first asset on the asset store and try to open them in Unity and it says “Sign in to access your assets”. I signed in with my email address and it won’t go away. An incredibly frustrating thing to get stuck on. I read that others had this issue and it was resolved when they used the email address instead of username to sign in. I’m already using the email address to sign in.
As mentioned in my comments first I had to remove all other versions of Unity, not just remove from hub, but actually uninstall them.
It still didn’t work and now the link did nothing. However, then I figured out, the workaround was to open Package Manager in Unity itself, via Windows > Package Manager. It then detected the asset and worked fine