Like most integrations you need to start with the authentication process. You will need to reach out to your account manager at Adform and have them generate a client ID and Client secret - these are the credentials you will need in order to build the connection between Symphony and Adform.
Once you have this information all you need to do is navigate to the 'Integration' section from the main menu. Then select 'Ext Account' and from the available options to the left hand side click on Adform.
Enter in the client ID and Client secret, then save.