Usually, the quickest fix for this problem is to check out with another browser, it's possible your current browser isn’t the latest version with the latest security updates.
If this doesn't work for you, please try one of the following which may help further:
- Clear your browser cache
- Make sure your browser isn't blocking " popups “ - PayPal needs to open in a popup box for you to log into
- Please ensure you’ve checked a shipping option - you cannot checkout unless a shipping option is selected
- You need to agree to the terms and conditions, this is done by ticking the box just above the login to PayPal button