Hi @sjungers,
You should register each app separately (different client id/secret). Let’s say we have a regular web app for admin, a web app for employees, and a SPA for customers. Those would require you set up three different applications/clients in Auth0. Then, if they all send requests to the same API, you would register a single API with Auth0.
You also might want to set up a machine to machine application.
These docs might also help, although they use some outdated flows and SDKs.