PayPal is a online payments system that supports online money transfers.
Use PayPal to enable the clients to book and make payments for their appointments through the online Booking page or Calendar.
To Integrate :
Go to Integrations >> Pay Pal
Basically, used for collecting payments from your clients when an booking and event is scheduled. Now, you just have to fill up the PayPal production Client Id then click on Save button.
Also, here is the video tutorial for your reference