You do need a personal chipcard. With its number you can subscribe.

Good afternoon daryasary and welcome to the NS Community.

As Thom has already mentioned, you do need a personal OV-chipcard in order to purchase an OV-fiets subscription. You can combine that however, but you'll need a working Mijn NS account for it first. For that problem, I would suggest contacting our Customer Service. My colleagues can take a look at the situation. You can reach them by phone, via Social Media or chat. All contact details can be found here.

Check your personal data in your MIjnNS account. If there are fields blank fill those, this could be your date of birth of phone number. 

Thank you @Momo, this comment solved my problem.