If you get an error like “Application Blocked by Security Settings”, follow these directions.
Open the Java Control Panel (in Start Menu → Control Panel)
Then switch to the Security tab, and (near the bottom) “Edit Site List”.
Now WebNow should load, if you go to its site: https://imagenow.umn.edu/webnow/
It does still pop up a security confirmation box where you have to check a box to proceed, but you should then get the login page.