I’m not sure they really care about the credit score number as much as SOME of the information that goes into it. For instance, your credit score reflects inquiries which a landlord wouldn’t likely care about. OTOH, seeing that you are current on loans and credit cards without any late payments tells the landlord that you are a reasonably safe bet to pay the rent on time. That’s really what they are trying to deduce by reviewing your credit.
The free online version contains the same information as the one that they are able to obtain on their own.