To install BuddyPress, go to Plugins > Add new and search for “BuddyPress”. Once you find the plugin in the search results, install it and activate it.
Next go to settings > buddypress and enable the components you need. In the "Options" tab, change the template to "Buddypress legacy"
To add the author block in listing page, go to Listing types > Edit your listing type > Single page tab > Content and tabs
Select “Author” in the dropdown and click add block