Without seeing the broken section of your Keter work table it is hard to make a recommendation on your specific repair.
My general recommendation concerning plastic repair is to weld and use the stainless steel sheeting for reinforcement. If you have enough room to build up the weld, the repair can be stronger than the surrounding material.
I would practice on some scrap material prior to working on something of value. This kit should be helpful, and for only $15, you can learn a new skill.
VEVOR Plastic Welder Kit, 60W/100W Dual-Power Plastic Welding Soldering Iron with 3 Welding Tips and 20 Welding Rods, Professional Plastic Repair Welding Tool for Car Bumper, Kayaks, Toys, Electronics - Amazon.com
a.co