In the case that your Apple Watch's battery dies before your round ends, the below steps will walk you through how to sync later:
Step 1 – End Round
When your Apple Watch battery depletes, click the drop-down in the top left-hand corner of the iPhone screen and select "End Round" at the bottom.
Step 2 – End Round
Open up the Arccos Caddie app on the iPhone and select sync later.
Step 3 – End Round
Sync later should only be used when the Watch has died mid-round. To continue the Sync Later process, select OK. Once your watch battery is sufficiently charged, proceed onto step 4.
Step 4 –Resume and Sync Watch Round
When your Apple Watch battery is sufficiently charged, select Resume and Sync Watch Round on the Activity page.
When the round has been resumed, select End round and then select Sync Round (with the Arccos Caddie app on the Apple Watch open).
Note: Another round cannot be started with the Arccos Apple Watch in shot detection mode while there is a round in the queue waiting to sync. You can start another round if you are using the iPhone to detect your shots.