Hi guys I preordered Witcher 3 recently with Paypal, I received the Paypal receipt soon after the purchase as normal, but the Order Summary from GOG.com has not arrived, as a result the game does not appear in my accounts library. please help any advice would be appreciated, thanks!

It might be worth contacting GOG directly for the fastest response. Go to: http://www.gog.com/support/contact and select "My orders, payments and downloading games".

Try:

https://secure.gog.com/en/account/refresh/

If that doesn't help, you'll need to contact GOG support.