Hi and welcome.
The site tells many things and offers a datasheet to the shield.
Telling us you did all you can, doesn't tell us what you actually did or did not do.
The datasheet shows the presence of jumpers (solder pads really), which will enable or disable certain functions.
And you are told multiple times on the site as well as in the datasheet, that you need to power the shield and display using an external 5 Volts 1 Ampere power supply, because this kind of power can't be drawn form a (any) Arduino.
So did you check the jumper settings, and did you use an external power supply for the shield ?