long-term stay protection

[Suzie119]

Hello - My AirBnb property is mostly used for guest in for business, training, and hospitals vs. vacationing. I have a guest looking to book for 4 months. I am perfectly fine doing this but would like her to do a credit check and to sign a short term lease. The AirBnb guest massaging tool doesn't allow me to send links thru and doesn't allow guest to send their cell or email. How does a host run credit checks and send leases?
*Property is in Baltimore MD. 

[Emiel1]

@Suzie119 

You can only sent attachments when the reservation is confirmed.

It must be mentioned in the listing guests need to sign a lease.