Modules downloadable from this website were made for old Slax versions (7.x) and they may not work on current Slax 9.x.
For Slax 9, use 'apt' to install software, there is no need for dedicated module repository anymore.
Extend Slax by modules
Additional software for Slax is provided in the form of modules. Copy your downloaded modules to the /slax/modules directory on your USB device in order to get it activated automatically during boot. Alternatively, you can use Software Center while running Slax to activate and deactivate Slax modules online. Read the documentation in order to understand how to use and even build and share your own Slax modules.