Go to Connection and create a new Marketo connection
Next, select add a new Account
Next, enter the Marketo connection information here. See this article for more details on getting information from Marketo.
Next, you will see an option to map fields from Lattice to Marketo
This is optional and you can leave it as it is
Finally, you should see a new connection tile in lattice.
You are all set and you should be able to launch campaigns now