Usually you should leave the player grouping to "platform ID". Some tournaments (e.g. RLCS) make players use a pool of generic Steam accounts, meaning the same player could end up using 2 different accounts in 2 series. That's when the "Player name" grouping comes in handy.

Team identification

Usually you should leave the team grouping to "players".

In some tournaments/leagues, teams allow player rotation, or a sub can replace a placayer. in which case teams are identified by players and not by distinct players.

A Teams has the same distinct set of players