Yep, it's OK. Paypal payment page gives an option to pay off with credit card. So, even if a user don't possess a paypal account, he can still pay using CC. It's advised that you let your customers know (at your sales page) that they can still process payment without CC.
Example: Take a look at Ste Fishkin sales page: http://www.cashgrabkeywords.com/checkout/?add-to-cart=27 (Scroll down to the bottom)
I can't activate my stripe account? So my website doesn't support credit card payments, but only support Paypal, is it OK?