You can offer PayPal Later (PayPal 4-installment payments) by enabling PayPal Later from the Merchant Back Office. The procedure is described in the Enable the PayPal Pay Later payment button section of the PayPal documentation: https://scelliuspaiement.labanquepostale.fr/doc/en-EN/payment-method/paypal/redirection-form/sitemap.html

When the buyer selects PayPal as the payment method on Scellius, they are then redirected to the PayPal website. At this point, PayPal displays whether or not the buyer can pay in installments.

Whether the buyer selects the PayPal payment button or the PayPal Later button on the merchant’s site, PayPal decides whether the 4-installment payment option will be offered to the buyer.

If the buyer chooses to pay in installments, the merchant will not see this detail in the Merchant Back Office.