I’m having trouble too, don’t know if you ever solved it but I believe you need to base64-encode username:password not username@password.
But I am not able to get it to work either. I wasn’t trying GET, as apparently that should work even without authorization. I tried -X OPTIONS, and on rest api url …/wp-json/wp/v2/posts, WP documentation says supposed to get back the schema of available fields. I can’t get anything but 403 Forbidden, even though viewing the url in a browser works
