Today (June 19) Apilio only accepts GET requests from IFTTT and other services. Certain customers would appreciate the ability to send POST requests to Apilio.
A word on the HTTP method: Yes, currently you have to use GET. I know that this is not quite correct from a purist RESTful interpretation - actually, it should be implemented as PATCH method (https://tools.ietf.org/html/rfc5789). I chose GET to simplify the setup process for non-technical users (because GET might sound familiar to most).