Invalid code signature preventing kernel extension from loading on macOS Sierra
I think I've got this to to work. Further to Jason Conrad's answer above, ATTO seem to have rolled the SH 1068 driver into the SH 2068 package.

Now, why they don't make this clear to anyone without actually downloading the driver and attempting to install, I don't know.

What I do know is that after installing the driver for the SH 2068 (that is signed, so works on Sierra) I can now see my LTO tape library.

Grab the installers from here:
https://www.atto.com/downloads/165/