Go to admin panel->Settings->Ads Settings
Select Ads Type and Paste it Id
for example( if you select banner type admob enter admob banner id)

Then Set Ids in Andoird Sid
if You use Admob set your Admob App ID in string.xml
if you use Unity Ads set Your Game Id in string.xml
if You use Aplovin MAX or Applovin Set your SDK Key in string.xml and Review Key In Gradle File

If you want to use Mediation

1.  Admob + Applovin
2. Admob + IronSource
3. Admob + Unity Ads
4. Applovin MAX + Admob
5. Applovin MAX + Unity Ads
6. Applovin MAX + IronSource