Return it for an indoor timer. It sounds like you got an out door ICC. Or if you want to deal with it. You should go buy a pigtail, basically that is an extension cable with loose wires on the end of it. Push the end of the pigtail with the loose cable side into the opening of the Hunter ICC, make the wire connections with wire nuts, close the compartment, and then plug it in. This is a pretty easy deal. Don't plug in the pigtail until you have finished all other wire connections.
Good Luck
Do not use the transformer from your pro-c. Don't, don't, don't. The reason is that the pro c indoor is on a transformer that is already stepped down power. The Outdoor unit has a transformer in it and needs to have 110 to step it down.
Dan