How to get the "Authorization header" for the create instant meeting API?


We are working on a small project in which we want the feature of video conferencing. I want to know 3 things:

1) How to get the "Authorization header" to create an instant meeting.

2) How many simultaneous meetings can a user host?

3) Is it possible that a user can create an instant meeting, without having to explicitly register on Team Viewer. We don't want our users to go through all that. We just want to them to click a button and a new meeting. If this is Possible then How?