Are you able to log in to your Xapo account in the pop up and select the wallet you wish to pay for? Also, I'm assuming you have enough funds to pay for the purchase too correct? I've notified our team to look into this for you.
Yes, I'm able to log in to my Xapo account in the pop up and I have enough funds to pay for the purchase. It seems that the pop up is too low and does not fit on the screen and I can't see the "Pay" button (tried on different browsers and different screen resolutions). Everything works fine for other digital goods in the "Xapo world".