Everything was wired accordingly to this schematic: https://camo.githubusercontent.com/4347b256f5ea0c2b7b98a872738b347d00193dec57eff10f279e5ee005385592/68747470733a2f2f692e696d6775722e636f6d2f35614b4c5270302e706e67
I've checked my connections multiple times and I'm sure that everything is connected as it should be. I'm not sure if I have to choose Atmega32 from MightyCore library or if I have to install a different one.