If you check the use of [FirebaseAdMob ver2.00] library,
When using a file downloaded from [B4A Sdk Manager Download:Android SDK Platform 28~30],
an error occurs : [Maven artifact not found]
Error example)
B4A Menu - Tools - Configure path - android.jar: C:\SDK DownloadPath\AndRoid\platforms\android-29 or 30
Resolution:
1) Goto:
https://www.b4x.com/b4a.html
2) 2. Android SDK + Required Resources
3) Download Android SDK Command line tools
4) Download the required resources.
5) unzip 3),4) example) C:\Android
6) B4A Menu - Tools - Configure path - android.jar: C:\AndRoid\platforms\android-30
No Errors.
I don't know the cause.