Hiya Andrej,
There are provisions on the landing page of PayPal that have links to tell them this, they just need to look around the page. You may want to add some info on your checkout page to let them know this also. No account is needed, they can check out with their credit card or debit card same as they would any other business.
Best way to know exactly what it says is to add some things to your shopping cart and hit the checkout button and see what that PayPal page has on it. Might even be worth putting a screenshot of the small area that shows them what to click to do a non paypal checkout.
Hope that helps