The RCCG payment portal can accept any amount of transaction you intend to make, However, your bank can place a transaction limit on your card.
If you find yourself in that category, you can talk to your bank to increase your card transaction limit to accomodate the amount you intend to pay or you can still pay split your payments instalmentally on the payment portal here however the number of times you want to.
For example, If your Total Tour Cost is 4000USD, you can pay 1500USD today, 1500USD tomorrow and 1000USD the next depending on your choice.