In order to be approved for a Dutch health insurance, you need to have a residence permit.
You also need to have 1 of the following: an income, benefits, a scholarship, or a Dutch inhabitant who guarantees your expenses.

It seems that your stay in Holland hasn't been approved yet. Which means you don't have a VISA/residence permit. Therefore Dutch health insurance companies will deny your request.

Thank you bkkjourney for your fast reply. In my mind, i am approved as all the information that i got said that i only need to register to the city hall to get the BSN number, after which everything is just simple formality. Anyway, from what i understand from you is that next step would be to go to the IND office in Zwolle.

By such and with all respect and good will, i can say that the dutch guvernment is not prepared at all or they refuse to provide accurate information.

The IND office which i called a few months ago, said that i don't really need a residence permit for there beeing an european citizen, it is enough to register at the city hall after which all health insurance companies ought to accept me. Besides this, i can't even open a bank account.

You don't need a visa for travelling to Holland, but for health insurance you need to be working in Holland or be a resident. You have a legal stay in Holland, but i don't think you are considered to be a resident. So probably that is the reason you can't get insurance.

For the time being it is possible to get an insurance at Oom Verzekeringen. But i think you should apply for a residence permit. When you get that you can (have to) get Dutch insurance.