*Michael
Hi, the app is in my application folder and unzipped (as you can see on the screenshot). Don't know what's the issue but V4 is OK for me ;-)

*Marc
Hi, yes i know retopo is the way to use them with subD tools, unfortunately. That's why i asked this question :-(

Hi Nico, hmmm well somehow it's not getting write permissions to write to the app bundle. Maybe it's some kind of sandbox setting in the new OS release?

re: low poly - that's not really a perfect match with a CAD tool like MoI since CAD is really focused on accuracy. You should expect to use a retopo process like Marc describes above to make low poly models. You can do it somewhat in MoI but it's not really focused on that area.

- Michael