The specs look like an electric golf cart, or a small electric forklift (a walk-behind).
Don't try running two controllers in parallel, they will fight each other, even though the motors are brushed (it's been tried...several different builders).
The price is tempting, but there have been plenty of times when me or a friend bought something that was "too cheap to pass up", and it was a total waste.
If you can afford to blow one or two up, go for it...experimenting is fun. If you have a 6000W job that needs to be done, find an existing brand and model that actually works.