EdTech Platform (Mobile App) (Working Title)

I want an education platform that provides below specifications:
Home Page that has the same buttons as shown in attached sketch.

The psychometric tests will be mind games.
The tables will be 20 users per table.
Tables will be held at the same time providing different MCQ at the same time (Live questions).
the expected amount of users to join at the same time should be approximately 150,000 (May increase).

That’s basically the application idea I would like to know how much would it cost me as (Cost plus calculation).

Much appreciated.

Best regards,
Salman AlHemaidhi