Machines will be inferior to free weight, its not "wrong" to use machines, its just that the results won't be as good.
If you can, try to incorporate free weights as much as you can, especially for the big compound movements. For smaller muscles and de-facto isolation movements, machines should be fine. (e.g. do squats instead of leg press, but whether you to DB curls or use a curl machine doesn't matter so much, if that made any sense)