Ok. The issue is likely that your IronPython paths are not set up correctly. The single-click Pollination installer is supposed to fix this for you but I guess it’s not working for some reason. CC: @MingboPeng .
In any event, you can manually fix it by following the first 3 steps of the instructions here BUT instead of just adding the path, you want to make sure that there is only one path to the Ladybug Tools site-packages, which should be:
C:\Program Files\ladybug_tools\python\Lib\site-packages
for your case.
After doing that and restarting Rhino, it should work.