I would be getting 5500zl gross - 3900zl net. Is it enough to live in Krakow?
You will be just fine!
Rent a room for around 900ZL, and you will have 3000ZL to have fun for.
I lived for 1.5 year in Krakow on a budget of 3000ZL after rent, and you live veryy good life! You could easily save like 500ZL pr. month even.
Can I ask which company you will come and work for?