GE has nothing to do with Canada - your background check/approval was cleared by the US only, so are approved as a trusted traveler to come into the US only. If you want similar trusted traveler status for Canada, you need Nexus, which is a joint program that clears you as a trusted traveler to Canada and the US.

Unfortunately, to get Nexus, you really did this the wrong way around. Nexus membership is half the cost of GE, and since Nexus requires the same background check/approval as GE, gets you the GE privileges at no additional cost. Unfortunately, doesn't work the other way around.

To get Nexus, you'd need to log onto GOES again and apply for Nexus, pay the fee, and wait for preliminary approval. At that point, you'd be invited to schedule an interview, which must be at a Nexus centre, since you'd need to do the interview process with the Canadian authorities. The trick is these centers are mostly in Canadian airports and at/near many Canada/US land borders. To use it at the airport, you'd need to make sure you go to a center with an iris scanner, as this is required for using Nexus to enter Canada when arriving by air.