Hey @Valerie51, thanks for posting
The Apple Watch Series 3 uses a technology we do not yet support so unfortunately it cannot be activated on our network at this time.
It's something we're going to work towards though as we build system functionality to support this technology. Keep an eye out on Fido.ca for any updates!
Also, keep in mind that you can still use the majority of the watch features by pairing it with your iPhone through Wi-Fi or Bluetooth! This allows you to use it's most popular features, calls will even work as long as your iPhone is nearby.