Google calendar API what are the limitations for a free account?

Question

Google Calendar

The context is this, you need to implement a preliminary record of customers on the site. We don’t have google workspace yet, but we are actively working on the free one, keeping tables.

I looked at the restrictions on the calendar api, and it became not at all clear that in order to use the api, google workspace is required?

In fact, 2 employees will have access to the calendar. Registration will take place on the site through the form. Busy days/hours will also be shown there. Will the API be free to use? The load is planned to be minimal.