There is no direct integration of audience manager with youtube. The only way DMP audiences can be activated on youtube is via google DBM destination.
There is a specific workflow that can take longer to make them available (up to one week) but all the work is on dbm side (a kind of advertiser mirroring to allow an approval flux to be compliant with gdpr).
From the AAM end, we can set up an S2S destination to send Audiences to DBM, you need to contact Customer Care team and share the DBM account ID. Rest of the workflow needs to be followed on the DBM side. Please contact Google support for more info on their side of the set up.