Pets created or rebuilt for Puppies take advantage of the category and subcategories available under JWM (or Barry K's implementation of it) to generate a two-pane menu: Category + slide out sub-categories displaying applications within that sub-category.
Xfce doesn't understand that system. When such a pet is installed into a Puppy using xfce, there's a good chance that most applications will be consigned to xfce's "Other" category: a not particularly user-friendly division.
Unashamedly stealing peebee's approach, the attachment to this post, can be installed to enable xfce to rationally handle Puppy categorizations. Download, unpack and follow the instructions.
Or install this pet.
In most instances use the pet. The difference is that doing it manually will enable you to create a backup of the file it will replace; and manually you could install it to /etc; while the pet installs to /root which has priority.
AppFinder was created to run under OS employing the Xfce window manager. I think it predates Whisker-Menu. In any event, it also is unable to properly handle applications written to conform to a JWM Puppy's categorization. Installing the Menu files per the included instructions 'unscrambles' the applications so that most won't be grouped in the 'Others' omelette.