They are open to all - their goal is infect as many people as possible with golf and that is why they do not put any restrictions to the access to the field. For the same reason, you can play with them all day long for 30 PLN, and rent a set of clubs for as little as 10 PLN. Those who have not had the opportunity to come into contact with golf will be shown the basics that will allow them to play on the field.
Enjoy!