I say ‘in Germany’ because there’s where I reside, a welfare state.
We don’t have 401K here, but public retirement systems, mandatory.
My employer also matches what I put in a small state pension system up to 50 euros. Not really much, better than nothing.
What number do I have to reach for a decent retirement? Retirement age: 67 years old.
Is it enough to save or do I have to invest?
Deutsche Rentenversicherung should send you an estimate of how much pension money you are going to receive every year. Assume that is optimistic, but a good baseline. I assume the matching program you mentioned is a Betriebliche Altersvorsorge (bAV)? Those usually also tell you how much they will pay you as a minimum, and another estimate based on normal economic growth.
Chances are that those together will not be enough to match your wage at retirement. So you should plan your savings so you can cover the difference for at least 16 years (which is the current life expectancy at 67 years old in Germany), and overshoot that if you can.