So that the property address for your transaction can be merged into various locations such as Forms, Templates as well as into the search integration the property address must be added as a Contact.
With Actionstep a contact must have an 'identity type' of either 'Indiviudal' or 'Company' and because a property address is not an individual you will be defaulted to have the Identity type as a company. Please treat the Identity type of 'company' for any contact that is not an individual.
Contacts that have the 'Identity type' of Company does not mean the contact is a real ABN/ACN company. Identity type selection simply changes the data you capture about the contact ie Individuals require first and last names, but companies just have a single text box.
Here is a short video on how that works