Once you have generated and approved your Phrasee content, you can navigate to AJO to set up your Campaign as you normally would, including configuring the audience and initial content.

The feature you are going to utilize is Content experiment, from the Action section of the Campaign creation process:

After pressing Create experiment, you need to choose a success metric:

Then add treatment to create versions for each of your different Phrasee content variants (up to 9 (treatment I) in total), ensuring to distribute audience evenly:

Now these are added, return to edit content:

Update the subject line (or body copy) of each treatment with a different variant from Phrasee:

After reviewing your content, you can Activate the campaign.