A better way to install the package

[redmondurbino-pk]

The instructions on how to install the package were misleading. Installing it via the GUI package manager does not work. Installing it by downloading it to your computer does not work, as then that creates a reference to the package that works only for you and not for other members of the development.
The best way is to just add an entry in Packages/manifest.json under dependencies
"com.unity.ads.ios-support" : "https://github.com/Unity-Technologies/com.unity.ads.ios-support.git?path=/com.unity.ads.ios-support",

[ariok]

Thank you. This is the correct way to install the package.