On-Site.com is a legitimate company (used to work there). They use a lot of integrations and third party services for credit/background checks. AFAIK, they were even using a vendor that would try to get court documents if records couldn’t be found for an individual. It was subsequently acquired by Realpage. (also a legitimate company) Surprised to hear anything is still running at the On-Site domain name, but checkin…
I don't have a link to the form, but it would be good to verify that this is legit (if that's something you would be able to do). It's an unusual workflow imo so I just wanted to double check