Drone does not take off, wants to fall on its side!

Put he drone in Loiter mode and then take off. This will allow PixHawk to take control of the drone stability. https://ardupilot.org/copter/docs/stabilize-mode.html

if that works, then perform in flight tuning procedure.

https://ardupilot.org/copter/docs/ac_rollpitchtuning.html

You can also post your log file. First delete all old log files and then just post the one where it crashes.

Upload the video on youtube and post the url here.

Also can you take pictures of your drone from the top and few more and post them here so we can check your wiring and prop orientation etc.