GPX upload help

Hi everyone I am hoping someone here can help me. I have a GPX file of a uo coming race I am trying to upload into Zwift workouts. I have followed all the steps and only get so far. The last step actually. The GPX map is being down loaded of mapometer and converted into a GPX file by a GPX conversion program. Has anyone uploaded their own workout before and if so is someone able to assist me in where I am going wrong. Thanks in advance.

Use this website - Convert GPX file to Zwift workout | What's on Zwift? - it’s easy to use and works well.