A Unity ID allows you to buy and/or subscribe to Unity products and services, shop in the Asset Store and participate in the Unity community.
Separate names with a comma.
So if the above solutions didn't work for anyone, this one might. After battling with this Issue for a day or so, I've found a method that should...
Holy S***. This just happened to me and I was pulling my hair out. This fixed the issue. Wtf Unity...