I will take a stab at this. First off, did you load the Halion Library Manager? Apparently this is key to using Flux. It is located in the install data of 9.5 but not sure about Elements.
Anyway, if you have installed this then you can open it and see an opening page in black with a blue tab in the upper left hand corner and the small icon of the Flux VST instrument. Clicking on the ‘Details’ tab on the far right, you should see the line appear ‘VST3 Presets for Flux’ and then the location of the FCP-SMT-232-HSSE-Flux-Presets.vstsound file. For some reason this file is kept within the Halion Library Manager folder located in C:Program Files/Steinberg/Halion Library Manager/FCP…etc., NOT IN THE TYPICAL VST SOUND FOLDER WHERE EVERYTHING ELSE IS STORED.
If you find this Halion Library Manager (ON YOUR DESKTOP) installed and the Flux icon displayed along with listed (under the ‘Details’ tab) the location of the Flux sound file (there is only one!) then you should be up and running. Remember, all of this Flux data is not going to install by installing 9.5, these extra installers are located in the ‘Cubase for Windows’ folder - and - you will have to install ‘HalionSonicSE’, the ‘Library Manager’, and finally ‘Register-Halion-Content’.
Also, you do understand that Flux is selected and run from within the Halion VST instrument window, right? It’s not a special GUI if you are looking for one. Take a look at a Youtube video, search Steinberg Flux.
I hope this helps.