Profile: You need to provide a profile if your tournament requires.
Ranking: This is for Friendship format. Ranking is your skill level in the tournament. It is the position, as a percentage. With rankings, you play against players who have similar rankings.
It is the ranking for your doubles team, not the ranking for your person. It is a self ranking, does not have to be accurate, does not have to be unique.
Ranking can be changed before enrollment.