Git clone the repository into your Wordpress application wp-content/plugins directory.
Once the plugin is installed and activated, select the "Dotmailer Contact Form 7 Plugin Settings" under the Settings menu.
Enter your Dotmailer api username and password. A list of address book IDs and names will be generated. You will need the address book ID of the address book you want to push the data into.
Create your contact form 7 form as normal, and ensure that any data you want to push up to Dotmailer has a name prefix of "dm_" and the name itself must match the contact field you have created in Dotmailer. For example if you have a contact field of "address_1", the form name needs to be dm_address_1.
There MUST be a field of dm_emailaddress with the users email.
Add a hidden field into the form with the name of "dm_addressbook" with a value of the ID of the addressbook.
Once this is all set and the form is submitted it should now push the data over to your Dotmailer address book.