Has anyone connected the API to Engage Voice?

We use the API to connect with our customers' RingCentral accounts to pull the Call Log Data. For some reason, I can't connect to this instance of RingCentral Engage Voice. The URL they use to manage this isn't RingCentral, but it's branded as RingCentral. Has anyone seen something like this before?

Here's the URL: https://portal.virtualacd.biz/manage/#/login

When I have them try to authorize our application via oauth, it just says the credentials are incorrect.

Anyone have any insight here? Thanks!