Once a competition is created, you can then assign teams to compete in that competition. Until that has been done, you cannot move forward.
Matches are also directly linked to competitions. Once you have at least two teams assigned to a competition, you can then create a match between those two teams.
Why is it important I create a competition?
Without a competition, you have no means of creating a match of two competing teams. Two teams must reside in the same competition before a match can be created for those two competing teams.