These maps are stored at: C:\Users\<user name>\AppData\Local\Itoo Software\Forest Pack Pro\maps
Recent libraries store their maps in a local folder, together the library files. For example: C:\Users\<user name>\AppData\Local\Itoo Software\Forest Pack Pro\lib\Presets\Cut Hedges\maps
By default, Forest adds all texture paths to the 3DS Max configuration. If not, you can add them at Customize -> Configure Project Paths -> External Files.