API to send requests anonymously?

I'm using an API which blocks me after 5 requests from the same IP adress. Sadly, a proxy doesn't help, even an anonymous proxy. They still know where I am and my original IP adress. How can I use a proxy anyways for that?

Another thing is that you can only get access to that API if you perform the request from a phone and not from a computer. How do they detect that?

Is there a way to bypass this? Thank you so much!

Regards, Chocrown