Board is finished, massive list of ERC errors

[Rene_Poschl]

Most of your problems might come from badly made symbols. (Bad decisions regarding electrical pin types.)

You might want to read these FAQ articles:

• Electrical type of schematic symbol pins (KiCad 4 and KiCad 5)
• Tutorial: How to make a symbol (KiCad v5.1.x)

And you also did not tell kicad where the supply of your power comes from resulting in “not driven” errors:

• ErrType(3): Pin connected to some others pins but no pin to drive it