Am I the only one suddenly not able to make purchases?

I have no problem adding the 24 Keys bundle and can also checkout.

Try again or

Website functionality : Should you have any webpage functionality issues then since functionality or lack of same could be a browser issue then also try another browser that you have not used before and with no extensions and all cookies accepted (my suggestions for alternative browsers would be e.g. Firefox, Chrome, Vivaldi browser and Opera browser ,depending on what you do not usually use)

The suggested browsers are what I expect will work if having never been installed before on the computer and then used as is with no extensions and all cookies accepted.