I know of two ways, at least on the Mac version. If you are using Windows, it may differ slightly. If you go to the File menu and select New, you will get the dialogue for creating a new timeline. To the far left is the Recent tab. If you hover your mouse over the document name in question, it shows you the full path. If you look at the top of your AT2 window you will see the name of the current document. Click the name and a small dialogue opens up which shows three fields: Name, Tags and Where. Click Where and you should see the full path.
In Windows, at the AT2 Recent/Example/Template choosing screen, if you hover over the project name, it pops up the location.