For all payments to be made via PayPal, you would require a Client ID and Secret. This post would help you out in the process of procuring your Client ID and Secret.
Steps For Creating Client ID and Secret For PayPal :
Step 1 : Log in to your PayPal developer account.
Step 2 : Go to the Applications (as shown below)
Step 3 : Now click the Create Application Button
Step 4: Enter a Application name And Create Application
Step 5 : Now, go to your created application and get the Client Id and Secret
Step 6: Finally, save your Client ID and Secret and send it.