REST API issues

Hello.
There is no documentation on REST API. I’m stuck with this feature. I created a very simple database table and am trying to reach this table from the mobile app. The mobile app complains about 404 error while trying to http GET record. The website also complains about the same: “HTTP/1.1” 404 114 “-” “okhttp/3.14.9″”. I’ve tried to verify URL by testing endpoint form your Data Explorer – Settings – REST API but your own test link says the link created by plugin is wrong – “{“code”:”rest_missing_callback_param”,”message”:”Missing parameter(s): col”,”data”:{“status”:400,”params”:[“col”]}}”.
I’m slightly disappointed with that, but since I’m new to your plugin I hope you will guide me to the solution.

Thank you.