only being shown with an executed contract

[Jonathan Hodge]

Can someone clarify the executed contract process for me?

"Both of the units are currently occupied by Tenants who are on a month to month contract. If you wanted the unit vacant you would just notify the tenants they have to move out with 30 days notice. Also, this property is only being shown with an executed contract...often times with Multi Family properties that is the case as they do not want to disturb the tenants."

We found a duplex that we are interested in. We would like to see the inside of what we are potentially buying. Do we have to make an offer that he accepts in order to tour this property? What if I walk in and change my mind?