In the Emailify export panel, select the Acoustic option from the dropdown list, when you're ready, click the Export For Acoustic button to start exporting the emails you've selected from Figma to HTML.

Once the HTML has been exported, you'll need to manually upload your HTML templates to Acoustic by clicking the Download your .zip file button in Emailify, unzipping that file after saving it to your computer, then you'll be able to upload the email .zip file(s) to Acoustic from the _zips (For upload to Acoustic) folder inside of your main unzipped folder.