Hi @Andy_Kerr_2260 welcome to Zwift forum.
Looking at the page for the Spartan Sport watch, it appears the watch is not able to send a heart rate signal that pairs directly to the Zwift app.
It appears the watch needs to pair via Bluetooth to Suunto’s own app.
Further, it looks like they have agreements with a handful of third-party apps, but your HR data syncs with them only after the workout’s over.
