Park wants to run credit check when I'm not buying anything.

My son and I have recently moved in with my boyfriend. He owns the mobile home, its fully paid for, but pays lot rent. I needed a letter from the park stating that me and my son live here now for his school, showing that our address has changed, but will still be in the same school district. The Management of the park is now making me fill out an application to run my credit for approval. I don't understand why this has to be done. I'm not purchasing anything. Is this legal for her to be doing this?

Can someone point me in the right direction.

Thank You

KJY