Atticus imports .docx files, but if your word processing program can’t Save As .docx, you can easily use Google Docs. Here’s how:
Import the file into Google Docs
Use this post to make a few tweaks to get your manuscript Atticus-ready: https://www.atticus.io/how-to-prepare-your-word-document-for-upload/
Click Files > Download it is a .docx file
If you have Pages, you should be able to Save As .docx, or you’ll need to use an online conversion tool to save as .docx instead.
This should only take a few minutes.