if your computer is using a realtek audio device then these can be troublesome due to recent security applied on newer realtek audio drivers.
one way around this is to try to use older versions of the drivers or generic drivers from microsoft but this is fidly and not really a long term solution.
I have recently found a solution to getting soundtap to work correctly on my asus rog that has realtek drivers, it also worked on my dell 7373 inspiron laptop so it has fixed the issue on two machines so far, does not mean it will work on all but please try this.
obviously make sure soundtap has been installed and registered,
then try this
open youtube and play a long video, we dont want it stopping while we are trying this fix, this will ensure there is audio being played at all times
now open soundtap , if there is no audio being seen
try this , go to the start menu on windows and right click and choose run
now paste this into the run box
rundll32.exe Shell32.dll,Control_RunDLL Mmsys.cpl,,1
press enter
the above will open a sound window which will be focused on the recording options, dont change anything just drag the window to the side and continue working