I'm assuming you sent a registration?
Anyway, these numbers will be used to determine a number of factors. Such as, getting an accurate count of how many people are willing to join and how many teams can be formed out of that pool of people on a per country basis. As well as deciding whether or not this tournament will be 3v3 or 4v4 and the limit on how many players can be on each team.
but... this is all just a guess so don't take my word for it...
Anyway, these numbers will be used to determine a number of factors. Such as, getting an accurate count of how many people are willing to join and how many teams can be formed out of that pool of people on a per country basis. As well as deciding whether or not this tournament will be 3v3 or 4v4 and the limit on how many players can be on each team.
but... this is all just a guess so don't take my word for it...