Atticus will only import one .docx file at a time. It might be easier to merge all the files together in Word using the method outlined here: https://learn.microsoft.com/en-us/office/troubleshoot/word/merge-word-documents
We also highly recommend following this tutorial on preparing your manuscript for upload so Atticus can process the information efficiently: https://www.atticus.io/how-to-prepare-your-word-document-for-upload/
If you do decide that you would rather upload each .docx file separately, that is also an option. To do this, you would need to:
Begin on the home page and click Upload a Book.
Select the .docx file for the first chapter, input relevant title data, and click 'Go Get Em Atticus'.
After your book has been imported, you’ll be taken directly to the Writing Tab where you can continue writing, editing, or make text formatting changes.
From here, Look for the three dots located next to the 'Add Chapter' button.
Click on the three dots to open a menu of additional options.
From the menu that appears, select 'Import Chapters' and select the next file.
Repeat steps 5 and 6 until all files are uploaded.