Hi,
The Sharp ViewcamZ is not listed as a supported camera on Apple's website. However, most tape based camera's are supported even if they are not on the list. Yours is 20 years old, so possibly its legacy age could be problematic -- hard to tell without fiddling with it a bit to see if you can get it working.
To cover the bases, take a look at this help menu link that describes how to import from a tape based camera:
https://help.apple.com/imovie/mac/10.1/#/mov6af9c94c1
Make sure that you have the correct (firewire) cable and that the cable and/or any adapters are not defective. Sometimes non-Apple adapters can cause problems. Also, try getting the tape running and see if that will trigger recognition.
Alternatively, you can try importing into the Photos app and then accessing your video from the Photos item in the iMovie sidebar. That's the recommended way. Or, you can drag the clips directly from Photos into iMovie.
Another way is to use the Image Capture app in the Utilities folder on your Mac to import the clips to your desktop, and from there drag the into iMovie.
-- Rich