Facebook and Mopub Bidding Blocks
You just need to drag Facebook ads adapter in Screen 1.
All Done Now Go to Mopub and select Network Section
After that in Network Name Select Facebook and go to apps and ads unit setup
Then Go to Facebook Audience Network and click on Bidding Setup Section and Copy all ads unit id.
After that just paste Facebook bidding ads unit id in mopub
Then Save it you ads is ready to show just add your test device in mopub and Facebook to check.
After test device added here you can see ads is showing