If you are an Ignite customer this integration will be set up by default for you.
Go to Realtair Accounts > Users and Groups > Offices > Search Offices : enter keyword > Select the office name > Settings
Set Agency code
Use the update office button
Go to Accounts > Users and groups > Search Users : enter keyword > Select user name > settings
Set Locke ID which is a unique ID from Ignite (an affiliate site of REA)