I am unable to set up let customers pay with credit card

Hi @sabina9511-proto , thanks for joining the Community

QuickBooks Online is a payment partner with PayPal and GoCardless for faster invoice payments. Which of these are you trying to set up, and do you receive any specific error when doing so? 

@sabina9511-proto 

If you are running a service business, you can use a proposal management app to integrate with QBO and accept payments by credit card.