For multiple scorers, you must be at a ground where there is online access in order to sync the scorecard to the server.
Before handing scoring to another person, you need to sync the scorecard, ideally at the end of an over.
When you save the scorecard, it must be unlocked so that another scorer has access to it - it cannot be unlocked by a different user. The new scorer should download the scorecard to get the latest update - depending on the connection speed, it does not always show the latest score when resuming (it may be one over behind) but the ball by ball view is normally up to date and the new scorer should be able to pick up from where one has left off.
The person who still has the scoring/syncing rights at the end of the match will be the one who can upload the results once online and logged into the app. The only way another scorer can do this is if the primary scorer presses “save and unlock” at the end of the game. The other scorer can then access the match.