The attached photo shows the rear of the fixture, which is 48” Long, 14” wide, and 3.5” deep. The wiring you see is standard hot (black) and neutral (white) connected to a quick disconnect wire harness. You can insert the wiring from the junction box directly into the matching slots on the harness – hot into the black hole and neutral into a white hole. The extra slots are for daisy-chaining to the next fixture (optional/advanced).
You remove the toolless wire access door and the green ground screw will be on the other side. This wiring access door is 3.5” from the end of the fixture. Using the layout for the space, the electrician can install junction boxes 3.5” from where the end of the fixture is supposed to be.