Hello, dear Luismigomez
The tracker is usually configured using SMS commands. In order for the tracker to connect, a SIM card must be installed in it. The commands are sent to the number of the SIM card used with the tracker. Therefore, if you want to use two trackers, it would be better and more convenient if a SIM card is installed in each tracker.
About the question related to email. Yes, you can create one account where you can create up to 30 units (1 unit can be created for free, more than 1 unit - with a Premium subscription)