Sync Custom Workouts to Apple TV

I now run Zwift on an ATV and own an old MacBook which is too slow to run Zwift on. I know that I should be able to create a custom workout on my MacBook and it should then sync with across my other devices - for me ATV. However, no matter what I do I never see any custom workouts on my ATV. I just tried with an iPad and this doesn’t sync in either direction (from iPad to ATV or from MacBook to iPad). What am I doing wrong?