I still have problems with the payment process in the premium library. Paying via PayPal does not work for me anymore since the end of October 2017. And now I can’t even pay by CreditCard, since the checkout page does not provide the credit card option. So actually, I can’t buy anything from the library.
Finally I was able to pay by PayPal. To be honest, my wife did it.
The difference between her payment and mine was, that she checked the terms and conditions again after returning from the PayPal page to the cart, where I thougt that my payment didn’t succeed. This behaviour is a little bit confusing in my eyes. I would expect, that checking the terms & condition and proceeding to PayPal would immediately start the download after successfull PayPal validation. But for the next time I’ll be aware of this behaviour.
BTW: CreditCard payment is still not available.
I had the same problem, and finally I was able to pay by Paypal with writing my name on the page My Account and of course checking the terms