Unfortunately, there's nothing you can do. Paypal only enables this option for users connecting from certain countries. For instance, if paypal detects that your IP address is from United States, then it will enable Guest Checkout, and for other countries it will be disabled. What I did to workaround this was to create an account in 2checkout and then installed the "WooCommerce 2Checkout Payment Gateway Free" plugin on my wordpress store. 2Checkout allows my users to pay either with a paypal account or directly with their debit/credit card, regardless of their country of residence.
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