A Leaders Card is an extra card for team leaders. This card is not the same as a Gothia Card and is not a replacement for the Gothia Card. The Gothia Card is for all participants, both players and leaders, while the Leaders Card gives the leaders access to extra things that's not included in the Gothia Card.
Every team registered in category A or B will receive two Leaders Cards for free. Are you more than two leaders you can purchase extra Leaders Cards for €40/$50 each. There are no requirements for leaders to buy the Leaders Card.