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.
Issue is fixed in Unity 2018.4.11f1 with Advertisement 3.3.0.
This ITMS-90809 problem still exists with Unity 2018.4.10f1 and Advertisement 3.2.0 (Package Manager)