adding a user based contract system into gaming website

I am creating a gaming website for football. I need it so a team manager can send a team invite which we will call a contract for them to join the team. This should include how many games he wishes the player to play with minimum being 5 and maximum being 99. After he has played this amount of games the player is released as a free agent. Everything is set up through sports press and its a word press website.

https://mg4.37d.myftpupload.com/