No order creation on PayPal payment

Hello,
I have setup the PayPal gateway of LearnPress for payment functionality by referring the 1st point from this reference, https://thimpress.com/learnpress-payment-settings-the-all-in-one-tutorial/. Tried making a test payment using my Sandbox account credentials. The payment from the PayPal side is being successful but the new order is not created at the LearnPress side. In the LearnPress admin page under the ‘Orders’ section, there is no creation of new order and also, no entry of the order in the database.