Can't seem to verify new host with vsphere web client

Trying to install Hotlink's Hybrid Express. Last step is to add their EC2 agent vm as a host. It works up to a point but ends up saying that it cannot verify the SSL cert. I've tried going into Vsphere web client going to manage vcenter and edit settings. It sees the host I'm trying to add and gives me a checkbox to verify it. I click, but it doesn't seem to take