Hi,
ok, so I have trouble publishing to IOS to test this, but indeed I thik all is available for you to show the banner.
you should use the action UnityAdsShowAd
the zoneID is your placementID,
you have created a banner id right?
as soon as I can publish and test, I'll confirm this, but it's 99% sure. things haven't changed since 2016 o that front, only the wording got different.
Bye,
Jean