I've moved your post to the "Other Products" forum, as Cadimage add-ons are not Graphisoft products.
Cadimage typically has very good technical support - I'd recommend contacting them if you don't get a response here. It would help others here to know if your are on Windows 10 and AC 21? And are you logged into your Windows machine as an administrator? Also, please identify your localization. I assume NZ or Austrailia since you say that the Cadimage installer is 'step 3 of new install' and I believe only NZ/AUS customers have some Cadimage products bundled? In that case you might also contact your reseller for tech support.
One of the forum moderators
AC 28 USA and earlier • macOS Sonoma 14.7.1, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB