I was going to suggest what you purchased. You can attach 2 of these together or to another piping.

The flex spout you bought will work but can you change the direction of the curved elbow at the bottom of your downspout? So that it empties out toward the garden instead of the driveway?

I thought they would have removed the elbow and connected to the flexible spout (can be extended 55 inches). There are adaptors that can be connected and then to a black corrugated with holes to disperse the gutter water so it won't all gush out the end.