You got it cheap because it's a cheap bike. Zoom fork, freewheel, quill stem, etc...


IMO the price of EUR 300 is about EUR 50 too high in comparison with other sources.


While that might look like a MTB, it's unlikely to hold up well to "true" off-road riding.
And the cheap suspension parts will make it heavy and energy-sapping to ride on roads.
Ride it gently.
Invest as little as possible in it.
And if you think MTBing is fun, start saving for a better bike.