I've been at it for ~5 hours now, trying to get my PS4 controller to work on my PC. My PS3 controllers aren't even recognised by my PC, so I just gave up and tried my PS4 controller. Now, my PC is able to recognise my PS4 controller as a "Wireless Controller", and the Control Panel shows that the PS4 controller inputs are going through to my PC perfectly. So it should, technically, be able to connect very easily. I downloaded Input Mapper to try my luck (after failing multiple times with various other means such as DS4Windows, DS4Tool, SCP variations, and so on. Nothing.), but yet again IM just doesn't show that my controller is connected as well. I have tried uninstalling my controller drivers and then reinstalling them, tried it with all my USB ports, tried with all my other cables, tried a different PS4 controller, restarting my computer multiple times, but still nothing. So I tried to connect my PS4 controller to my laptop instead, and it works perfectly.
Ods are that since you were trying other application, that they were not properly removed first. Since none of the other applications have installers they require manual removal of drivers from the driver store, and likely registry deletions. The issue appears to be the SCVB drivers included in InputMapper will not install if there are leftovers from previous applications around.
You'll have to find the controller listing in your Device Manager, right click on it, and uninstall it. It is possible it will be listed in multiple places. You'll have to make sure that you get the right one, or all of them. Once you've removed everything related to the controller, unplug it, restart, install IM, and plug it in again. Hopefully it will work.