Follow the vRA 7.4 docs to start using vRO plugins in vRA.
Run the Add a Puppet Enterprise (PE) primary server workflow provided by the Puppet vRO Plugin with these parameters:
Display Name for this Puppet master: The name for this primary server
Hostname or IP Address: The hostname or IP address of the PE master
SSH Port: 22
SSH and RBAC Username: The user you created
SSH and RBAC Password: The password you configured
Use sudo for shell commands on this master?: yes (no if using the root user)
After you have added the master endpoint, follow the Designing blueprints with Puppet features documentation.