How to add new users to a G Suite for Education account?

Question

My company is working on an e-learning website where schools can register and take online classes using Google Meet. We require the following flow :

1. When a school registers themselves to our app, the school is asked to create a G suite account (The school will need a G suite for Education account I believe?)
2. After that, our app adds new users to this account created by the School. So if there are 10 instructors in the School, we create 10 different users. (These users will not have pre-existing Google accounts. We want to create new user accounts with custom domains, like [email protected])
3. These individual instructors can then create Google meet events through our app, so that they can host meetings for their students.

I am wondering if this flow is at all possible. I understand that to add users to an account via APIs, I will first need to create a new Project in the Developers Console. Then I need to generate the Client ID and Client Secret, and use them to send requests to the Google APIs. But it is not practical to ask the schools to complete the above process by themselves, and provide me with their Client IDs and Secrets. So is there a way to add users to a school's G suite account on their behalf, without making them go through the whole process mentioned above?

PS - Is there way to create/request for a demo G suite for Education account for the purpose of testing and development, that does not require me to register an actual school?