Design a new cloud based application with multiple login mechanism

I recently switched to a new company where my manager wants me to develop entirely new cloud based project in MVC. I have never worked on a project from the start and I think this is a good opportunity for me to lead. However, I think the requirements of the clients are bit confusing.

Here is what he wants:

1. Client should be able to access the cloud hosted application from his network with single sign on. He wants to use his active directory for that.
2. There are different users in active directory, they will have different roles (I think we can handle this on database side. Create different roles and assign roles to users).
3. Client has to add vendor info in the application. But for this, system should send an email to vendor with the url of the cloud application. He wants user to login to the application using 2 Factor Authentication. So, send dummy password with url, and send OTP to his mobile number. Just like registering to any system.

Now my questions are:

Is it possible to have 2 different types of login mechanisms in the same application? SSO for client and 2FA for outside vendors?

If yes, could you please guide me in the right direction?

what things I need? Which framework, design pattern should I prefer?

How do I proceed ?