Goodnight. How many users can use my application with the free version?
As described on the pricing page, it is not based on the number of users. The principle is that if your app is a prototype, it can be tested for free. But when it is being used for real (Deployed), you should be on a paid plan.
As a practical constraint, a prototype app can have no more than 10 users. However, a deployed app with 5 users should still be on a paid plan. Hope this clarifies.