Some customers may get the notification "our system does not allow you to ship to these countries" when checkout by paypal.That's because shipping address is not  the same as the address country set in the user paypal account.
For example, if Paypal account country is HK, the transaction will fail if shipping address is UK or US.If Paypal account country is US, the transaction will fail if shipping address is UK or HK.
 
So ,please select the addss country set in the user paypal account as shipping address or select the address country and email us your order number and shipping address you wish by email ([email protected]).