The Adams trail a bike has stop tabs limiting the turning radius. With a large wheeled bike, your turn radius is not that great to begin with, so it's not a problem. But with a folding bike (smaller wheels), the smaller turn radius can potentially put you in a dangerous situation where your bike makes the turn, but the trail-a-bike doesn't (ie. tips over). I've had this happen while testing the setup around the neighborhood on my Brompton:



I ended up making a seat for my kid that fits on the top tube of the bike using the trail-a-bikes seatpost trailer mount: