Figured it out! I used the cord from a clock in my room and it plugged right into the back of the Gro Clock like it belonged there all along:)
Just in case anyone ever has the same issue but doesn't have a cord at home that will fit, it looks like you just have to buy a universal ac power adapter. I read a lot of reviews that stated just buying an outlet adapter wasn't sufficient because it didn't give the clock enough power to function as it was meant to.
Hope this can help someone in the future:) By the way, I LOVE this clock so far! I had a different one for my older daughter but this is much better.