Use the WEB API on a OnPremise Dynamics CRM

Hello,

We have a Dynamics CRM 2016 onPremise (version 8.1.1.1005) installed on an offline server wich provide a Web API.
We are installing Adobe Campaign (which is installed OnPremise on the same network than our CRM) and the connector need to use our CRM Web API. So we need to register an app to get a ClientId.

This is our situation :
- Our CRM is installed on an offline server
- We don't have an Active Directory Federation Services
- We have an Azure portal which can make app registrations

With that, is it possible to register an app to use our CRM Web API ?
If not, is there something we can do to make it work ?

Thank you !