The sequence of steps...
The MarpxPrivacySetup.exe pack can be downloaded from https://BuyExtremeEncryption.com. Sorry, we can't provide pictures because each different browser has its own way of downloading. Let's start at the point where you have located in Windows Explorer (or whatever) where your download is found.
Right click [VERY IMPORTANT -- RIGHT CLICK] on MarpxPrivacySetup.exe and in the popup click on Run as Administrator. A "preparing to install" popup shows briefly, then:
Click on Next. If you see this...
Whoops! Did you skip the Uninstall step? It's the same problem if you are given a choice to modify the existing program. In either case, back out and revisit Uninstall.
If all is going well, you are shown:
Read. Assuming you wish to continue, click the circle to the left of the I accept box. The Next button is no longer grayed out.
Click on Next.
Fill in whatever information you wish. Click Next.
If you want to change the location, do so. But any change needs to be to a location at which you are permitted to write files by the Microsoft security system. Click Next.
Review, then click Install. A temporary loading screen is in place briefly, followed by:
We suggest that you leave the Launch the program box checked. Click on Finish.
... and you are in the program.