Siri Shortcut to Post OmniFocus tasks to Habitica

Good afternoon.

I’m trying to figure out how to dump OmniFocus tasks to Habitica via Siri Shortcuts.
I’ve read the documentation but I’m not a programmer at all.
I’ve created the shortcut using the “Get Contents of URL” action is Siri Shortcuts and I get a “Not Found” error.

All the examples I can find are written in “pure code” and I’m afraid I’m missing some piece of the puzzle that is so simple no one feels the need to explain it. Can anyone help?

The Habitica documentation about required headers is here.
The full API Documentation is here.