To begin with, you may
You don't have to worry about any of the technical stuff - just follow the link and you're good to go! No need to install any packages or think about which orgs to install it on. The Web App version has exactly the same tools as the package, and is just as secure for your data as the package is. Therefore, you can be confident your information is safe.
OR
In order to start the App, you need to install the package on one of your orgs. Installing the package is a simple process that doesn't take long and is worth the effort to get the best of the App. Your data is safe and sound, locked away in the package with only you and those you give access to holding the key.