Hello extensa5
Don't get too confused by + and -.
In the second to last diagram, the black conductor is labelled + and the red one -. This is wrong.
If you plug everything together as mechanically possible, it will be fine.
Then wait until the sun shines on the panel and the battery will start to charge.
Best regards
Hannes
No, you don't need it. I ordered the cable to tinker with so that I don't have to cut up the original. I find compatibility between different products problematic.