I think you want to work with Evendate API documentations, right? For example, you want to make some requests and may be find errors. So, before you start. Open your hosts file and add one new line:
5.101.124.61 test.evendate.org
Added? Good boy. Now try to open test.evendate.org
and authorize with any oAuth provider.
I see you are in hurry. Not so fast. We have to read documentation before making requests.