How many limits calls per user?


I don’t understand limit api, there are ,for example,
15 for list (on 15 minutes) and
15 for credentials(15minutes) so i can make 30(on 15 minutes) or 15(on 15minutes)?

I’ve tried to click for 15 times on contact list api call and after 15th click i handle error message of limit rate exceedding.

Now i’ve tried to login and i expect to make others 15 attempts on login calls.
But i receive an error .