Step #1: Login to your PayPal Business Account
Step #2: Go to "Account settings"
Step #3: Go to "Account Settings" > ACCOUNT & SECURITY > Account access
Click "Update" link of "API access" as follows.
Step #4: Click "Manage PayPal checkout settings" as follows.
Step #5: Choose "Accept PayPal payments before API permissions or credentials are set up
(You can complete API setup later)" and click [Submit] button as follow.
Step #6: Notify your system administrator that the setup is complete.
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