De Noise-Photoshop Plug In won't install

New user here, please be - merciful? Thankyou.
Been using DeNoise and Sharpen for some weeks now, nearly all DeNoise which cleans up pix very nicely indeed. Been through a couple of updates, no issue.
HOWEVER. Due to drive space shortage I had to remove both apps from C: to D: drive. Completely uninstalled both, redownloaded the installers from Topaz site, installed to the new location.
Now I can’t get either to install the plug in to my copy of Photoshop. (Which is still on C:) C: is a small SSD so for speed reasons I don’t want to shift my (CS5) copy of photoshop to the D drive because it’s the old style HDD.
I never could get the plug in for Sharpen to install its PS plug in before the shift between drives but since I hardly ever use it I didn’t really care… But I DO use DeNoise for every single shot I process and the plug in became vital to my work flow.
What’s going on here with plug in installation?

Have you tried the option to reinstall the plugins from the Help menu.

The main reason why it doesn’t install is because PS is open at the time of installation.