http://www.eca.bc.ca/pages/directory#action=AdvancedSearch&cid=669&did=4&listingType=O Select your town and you can find licensed contractor for installation in your area.
I'm a new Clarity owner, just got one on Saturday. Before getting the car, I did some research and also asked my nephew who has a Bolt. He recommended Juicebox 40 Pro. I bought one from Amazon and had it installed Sunday morning. As soon as installation was done, I tried charging and it worked without any issue. Keep in mind that no matter how much amperage the charger has, it won't do any good if your car battery capacity is not high enough. Even though my charger can charge at 40A, I only set it at 30A, and it takes about 2 1/2 hours to fully charge.