Google Play Protect's new policy for custom DPC

Apparently, Google has a new policy that only approved DPCs can be installed through QR Provisioning; otherwise, their installation will be blocked.

Link: 

https://developers.google.com/android/play-protect/warning-dev-guidance#android_enterprise_dpc_enrollment

The problem is that I am not able to understand how to apply for DPC approval. I found this page, but still not able to find out where to apply. Your help is appreciated.

Thanks