While Odoo only includes Wire Transfer by default, the framework is modular and can be extended to include additional payment methods.
We have to install a PayPal payment processor a little differently because it is not a full application, but rather a module. We still need to go to Settings and Local Apps, but we will need to uncheck the Apps filter from the search.
After clearing the Apps filter, simply type in PayPal to see the standard Install button:
Once you've clicked ...