Fenerum can generate a link for the dedicated page where your client can put their credit card data. You should send this link to your customers. This link will be unique per-customer.
To do so go to the account page for the client for which you want this link.
Over there under the "Billing info" you will find a button "Add payment method". After clicking it you will need to choose your payment provider for which you want a link to be generated.
In the pop-up window you will find a link which you should send to your customer. After entering via this link the client will be able to put his or her credit card details into selected Payment Gateway and it will be connected to his or her Fenerum account.
Note that for QuickPay customers you will also need to specify a currency that a relevant subscription will have. For more info about QuickPay integration see this guide.