If you want to sell your product through coins, you need to specify the coins here. Only two coins are given here.

polygon
Ethereum.

In that step, this is not Coins. That's called Blockchain Network. Which Blockchain Network would you select.
If you select Ethereum, You have to pay gas fee & If you are use Polygon then It's a free blockchain network, You didn't need to pay gas fee.

Please Fix that information.