Right click on the icon and choose Properties.

Copy the Target path, excluding the 'LaunchLicenseServer.bat' section.

Open a Windows File Explorer and navigate to the above obtained path.

Find the LaunchLicenseServer.bat file and open in your favorite text editor.

There will be a line of code that looks like this:

start /B iexplore https://%LS_URL%:5814/autopass
Change the iexplore to firefox and save the file.
Test by clicking the icon on your desktop. If it does not launch APLS in FireFox, then you may have to put the full path to FireFox in that line of code, like this:

start /B ''C:Program Files (x86)Mozilla Firefoxfirefox.exe'' https://%LS_URL%:5814/autopass
Please note that depending on your installation of FireFox, the path may be different than this example.

You can use other browsers too, just change that code line to the executable for your browser of choice, however note that APLS documentation states that it supports IE, FireFox and Chrome.