In order to make files with CircularFLO that ready for sale with Amazon you will need to download and install Kindle Previewer 3.
It is free to download and use Kindle Previewer 3. The current version for Mac can be found here - https://www.amazon.com/gp/feature.html/?docId=1000765261 Kindle Previewer
CircularFLO automatically opens publications as fixed layout and reflowable ebooks files in Kindle Previewer 3 in order to convert your publications to Amazon file formats.