When you click Make Payment and the PayPal window opens, scroll down to see the options for Pay Later:

 

Pay in 4 allows you to pay for your purchase in 4 interest-free instalments. Your first instalment is due at the time you make your purchase. The next 3 instalments are due every 14 days after your first instalment.
 

Pay Monthly is a way to spread the cost of qualifying purchases between $199 - $10,000 USD into fixed monthly payments over terms ranging from 6 to 24 months, available to eligible customers during online checkout. Pay Monthly is an interest-bearing installment loan issued by PayPal’s bank partner, WebBank, with a fixed APR ranging from 9.99% - 35.99 % based on creditworthiness. Lower APRs may be offered as a promotion from time to time and are subject to eligibility and the terms of the offer.