I believe their app incorrectly handles the responses to authetication requests made to Windows.
I have a workaround, which while tedious seems to work both for simMarket and iniManager. Create yourself a new Local account in Windows and give it Administrator rights. Log off your normal account and log in to the new one. Go to simMarket or iniBuils website and download, install and run their app.
Log out from the new account and into your normal one (which mnust also have Adminstrator rights). Use a tool like "everything" to find the .exe for the app you are setting up and try to run it. At some point Windows will complain about your request and give you the option to grant yourself access to it. Grant yourself access, pin the exe to your Start Menu. You may see the app .exe in more than one location: why this is the case I don't know. The one I picked worked fine and since then I have not heard about any nukes launching spontaeously, so assume it was safe!
at this point you should be able to run your app as normal. On the next release, until the apps are fixed,my guess is the store will break and you'll need to repeat my steps.