How House contract and agency acceptance form works?

I need a little advice here regarding house rent contract rules in NL.

Recently I did a viewing of one apartment and I liked it so I provided required documents to the housing agency but received no response from their side for a week even after following up.

Finally after a week they sent me a ‘Concept’/sample copy of house contract. I got to know that they have policy of releasing deposit after 3 months which I am not comfortable with. So I don’t want to sign the final contract and rent that apartment anymore, also communicated same to them but they are saying you cannot cancel the lease now because you accepted the acceptance form.

Since I haven’t signed a final house contract letter I hope the agency can’t force me to take an apartment ? Can anyone help me with your suggestions?

Note: I have only signed a agency house acceptance form (one page form) which is not a contract because it doesn’t have any financial terms and deposit related policy.

Thanks a lot for your help !