Azure AD expertise

Job ID: 33150545

Budget: ₹1,000 – ₹3,000 INR

I want to build web portal registered in Tenant A. Other tenants can login to the portal using their own credentials. The user will access their own resource (e.g.App Insights)from the portal to query and won't be using Tenant A's App Insights. How do we achieve this in Azure AD. Any help will be help with documentation/links to the documentation.
Related categories: C# Programming Azure Microsoft Azure