If WebOS Quick Install isn't working, the first place you should go is the WOSQI official thread.
Originally Posted by lovepre100
The simple fact of the matter is the current version of WOSQI will work on pretty well any Windows, Mac or Ubuntu computer, however, as not all computers are alike, setup can be rocky.
The official WOSQI thread is full of posts from people who encounter errors and posts of solutions that work for individuals. To make things even easier for people, I've even created a comprehensive step-by-step guide in the for of an app available for all on the App Catalog. It specifically includes an interactive problem troubleshooter for situations like this. And in fact, installing the SDK is one of the last-ditch options (as users generally don't want the 200MB+ download, nor all the extra stuff the SDK installs).
And on another point that's been raised in this thread, it's worth noting that every other alternative way to install Preware will require a novacom connection (which is what's currently listing no devices as detected). So in general, if WOSQI isn't working, the alternatives won't work either. And conversely, if after you install the SDK novacom gets fixed, then WOSQI will work again.