Now you probably know why the price has come way down from what they used to be.
They used to work, and now they don't, but they will sell the kits to you for cheap!
The electric window motors draw a lot of current, are your wires big enough? The wires to my window motors were at least 14 gauge, and may have been 12 gauge.

Its tough to beat the OEM stuff. The last one I used the power assembly from a 5th Ave, and swapped it into the location of the original unit.

Most of the modern stuff uses a centered beam that attaches to the top and the bottom of the inner door frame. A plastic track slides on the beam. The motor pushes the track up, or pulls the track down. The window channel attaches to the track. Gene