Do I have to register my players?
In TeamXp you have for different types of registration. This means that, depending on the level of security you need, you can choose the one you consider is best for your exercise.
If you want your players to be recognized inside the system you need to create your Teams. This way you can pre assign positions/roles and put them in different teams. You can also allow only whitelisted players in your exercise so that only the people that you have previously uploaded in Teams can access the exercise.