I saw the specs for the folding bike (20" wheel, 48T sprocket, rear 14T-28T).

This would put 6th gear at 68.5 gear inches (48T/14T x 20"), and 5th gear a little lower (60.0" for 16T cog in 5th). I would have expected top gear to be a little higher than this, but the manufacturer probably expects the bicycle to see light use by bicyclists not concerned about setting speed records.

The GT Traffic specs put the gearing at 77.6, so this would be gear 7 (higher than 6) or even a little higher on your current bike. The GT looks like a decent bike for the price that will meet your needs (and available in a medium size to fit 5'5" riders).

I'm not sure where your are located - larger cities often have bicycle coops with space to work on bikes with tools and volunteers to give advice. If there is one you can go to:
(a) They usually sell used bikes very cheaply, and will help you make any repairs needed. They probably have a suitable bike. Or

(b) You can buy the GT and they can help you change the rear freewheel for 20T or 21T to give it more normal gearing. The bike coop will probably have the parts (freewheel, extra chain links to fit larger gear) and tools needed.

This change (replace freewheel, adjust chain and brakes for new wheel position) are not difficult, but it sounds like bicycle repair is still new to you so you might see what help is available locally.