I consider this to be a bug.
It seems the detection routine that ensures the PortableApps packager is not launched from C:\Program Files is flawed.
Any folder name starting with the string "Program Files" on my root is getting blocked, such as "C:\Program Files (portable)" which I had just created to store all my portable apps.
From my reading of https://portableapps.com/node/33575 , there seems to be legitimate reasons to block "C:\Program Files" and I guess "C:\Program Files (x86)" as well on x64 systems.
However, IMHO, the package should not block a folder that is not a system folder even though it has "Program Files" as part of the name. I should be able to use C:\Programs Files blablabla" or whatever variation of my choosing.
It's a known issue with the PA.c Launcher (lines 11 to 14 in PathChecks.nsh for the curious). It was also an issue in the PA.c Installer that was later corrected but all apps built before the correction will still be unable to install to that location. Once we fix the PA.c Launcher it will be a couple years before all 300+ affected apps are updated with new launchers that do not suffer from this issue.
I'd highly suggest using C:\PortableApps for all your portable software. It won't experience this bug and every installer will automatically find it when you run it since C:\PortableApps is one of the paths searched for existence.
Sometimes, the impossible can become possible, if you're awesome!