Integrate Auth0 with multiple groups

Hello, I am new to this community and implementing auth0 for the first time. I really love the product but can’t figure out a couple of things because of some misleading points or documents.

I am trying to implement a B2E scenario were I (X) is a company that exposes some API (s) to their registered partners/organizations (0). And these partners consume these APIs with their own credentials and all employee (E) can share the same client secret and key.

After reading the documentation of Auth0,

X → Will treat itself as a Tenant

0 → every time a company onboarding themselves using our web portal and provides their own credentials such as client secret and key to generating the access token, Do I need to create an application or organization?

E → How the role management can fit here for each organization? There can be two roles i.e. Admin and Developers

Website → Also, The above scenario is M2M, How can I connect with the website OAuth login? So that organization employees can log in to our onboarding platform and manage their users / secret keys and this will reflect in the M2M database as well.

For website, I am using react.js framework where as for backend I am using spring boot java

I am confused here. Any lead would be a great help. Thanks