Azure Active Directory - What to set for Redirect URI for Power Flow call to Business Central custom API with OAUTH2

Question

I'm trying to create a flow which calls a custom API I wrote in Business Central. I have an application set up in AAD which I intend to give OAUTH permission to my flow to access the API. In my flow I have one HTTP request which calls AAD to get the token - this works. I have a second HTTP request to the actual API. When I try to call the API I get an error:

<error xmlns="http://docs.oasis-open.org/odata/ns/metadata"><code>Unauthorized</code><message>The credentials provided are incorrect</message></error>

I know I need to set up the Azure Active Directory Application in Business Central to give access to the API, but I am getting hung up on the Redirect URI in AAD.

What am I supposed to put as the redirect URI in AAD for this "application". I'm not sure what the application is in my case, I dont have a web app, I'm just calling the API from a flow. Is there somewhere I can get the Redirect URI from the HTTP connector in Flow? Do I need to create a custom connector instead? Am I going about this all wrong??

Thanks!