I have purchased wallet cards for my employees but when they request it, they are asked to pay again. Why is this happening?

When you make a payment, as a group leader / employer, the wallet cards credits become available in your account. This means, that in order to receive them, you need to request them from your account (the account that made the purchase).

If these cards are requested by one of the workers that is taking the training, that is a different account that has no free wallet cards credits, which is why the worker is asked to make a payment.