In the PayPal Config tab, ensure you enter your own PayPal email ID (also the primary currency you use with PayPal). It simply won't work with the default email ID from install.
If you know how to use the PayPal "sandbox", you can test all you like after setting up a (free) developer account with PayPal. The sandbox is used to test and debug this module. If not, get a friend to make some test donations, unless you have a second PayPal account to use. You can refund these through your PayPal account, without any fees or penalties.
Check the other options in admin for setting up the Module and Block appearance.
Your monthly goals are displayed under Block configuration.
When you are happy with your setup, make sure you have activated the Treasury module.