Create an account or login if already registered.
Navigate to dashboard and find the "Tokenization key" in Dashboard > Settings > API keys.
Paste Tokanize key to src > pages > checkout > checkout.ts.
If you want PayPal integration inside braintree payments, go to Sandbox Accounts(obtained from https://www.sandbox.paypal.com/myaccount/activity\and create a sandbox business and personal test accounts.
Note that if you want to move from Sandbox to Production, you should go to My Apps & Credentials (obtained from https://developer.paypal.com/developer/applications/.
To add PayPal integration inside braintree payments, navigate to Dashboard > Settings > Processing, and enable customers to pay with PayPal by adding PayPal credentials.