Mine is on the right side--passenger side--when standing at the back of the car.
It is more of an expansion tank than anything else, as it is open to the atmosphere via the FST (funnel shaped thing) which is one of the three connection points on the canister.
If my memory serves me correctly, two lines from that expansion tank connect to small steel lines on the fuel tank. If the fuel expands or evaporates in the tank, it "overflows" into that expansion tank. If the expansion tank gets too full, it drains out the FST...or something similar.
When I restored my car, my original expansion tank had small brass tubes as connection points, and fuel-grade hose connected these points to the points on the fuel tank, while the third one went to the FST. I had, when they were exceeding cheap, bought the MB OEM replacement. Imagine my surprise when it seemed to be a one-pieced molded thing of exceeding lower quality than the one I had. So, I didn't install it. What I did do was cut it open! Nothing inside. No carbon filters or anything. It's merely an expansion tank much the same as the one for your radiator in the engine compartment.
Mine's a January 1969 build, so emissions regulations may have changed to something different after that time.