You are required to make an initial payment of $7.5 for each challenge. Once you have successfully completed the challenge, the remaining amount must be paid after you get funded.
For example: 5k account original price is $69, you pay with "Pay After Pass" method first $7.5. Then, if you pass the challenge and want to continue with funded account, you will have to pay the rest - $61.5 in this case. And it goes with every other account with their original prices.