Battery is too low to fly

Example: I have installed it this way (as usual). And then Power Brick wires go to the Cube. Also 2 becs takes power from the center plate (gremsy and Herelink air unit).
Is it OK or do I need to change something?

You may have a look at the user manual
https://docs.cubepilot.org/user-guides/autopilot/the-cube-user-manual#power-module-connection

The power module should be placed between battery and loads.

Okey. Can I install like this (separate cables)? Because XT 60 connectors is small to install on the original Power cable. And I use two batteries so I have to buy one Power Brick more. Is it right ?

100% of the power must flow THROUGH the current sensor. There can be no other connection between the batteries and your power distribution.

That being said, it is pretty obvious from your choice of ESC that the power brick mini is too small to handle the amount of current you will be drawing.