This doc,
formatting link
page 2, tells me to unzip a file to create a new folder
C:\Program Files\LTC\LTspiceXVII\lib\sym\CreeDiodes which I have done. It's full of .asy files. Then if I go to the Components icon, the gate symbol, I should see
[CreeDiodes]
as a category, just like I see [Opamps]. But it's not there.
I created folder \CreeDiodes in the \lib\sym of both the old and new Spice versions. No luck.