Well, first thing is, you may not use everything, just because it came in the kit.
The first thing is to determine what you need to put the motor just right into the space between the rear dropouts of the bike.
You might need a spacer washer, or not, on the gear side. Gotta have the gears not rubbing right? Or the forks may be wider than the shoulder cut into the axle, requiring a spacer washer. Or it may be too big. Alloy frames can bend out a very small bit, like 2mm each side max. A steel frame can just be bent out to what you need, like 5 mm per side.
Then it's down to fitting the washers and torque arm to the outside. If you have just one torque arm, put it on the side without the derailur if it fits better there. Yes, this is a pain because you have to take the plugs off the wires to get washers and torque arms and nuts on that side.
At this point, the fit of the first washer touching the frame is cruicial. On rear dropouts, this is usually no problem. The main thing is the washer must lay perfectly flat But you might need a washer under the torque arm to make it lay flat if something on the frame sticks out. You might need to grind a notch in the arm or the washer, for example if the derailur interferes.
So do whatever looks like it fits good. Bottom line, you need at least a torque arm followed by a nut on one side. And a washer followed by a nut on the other side. Which washers you use is your choice, depending on how you see them fit the best.
The torque washers with the tabs are optional for sure. They are utterly useless as a torque controller. But they make good spacers if you need to get a torque arm clear of something on the frame. You can use the split lock washers if you have enough axle length to fit them and the nut.
THE LIPO RULES. NEVER ABOVE 4.3V NEVER BELOW 2.7V DON'T PUNCTURE
Ideal charging /discharging range for Lipo, 3.65v minimum 4.1v maximum
See battery technology section, FAQ thread at the top of the page for lipo noob info.