From the previous step, note the identifier from the newly created APFS Container (shown in the red box below) and use it in place of ‘identifier’ in the final Terminal command, shown below the screenshot.

In Terminal type the following command and hit the Return key: diskutil apfs addVolume identifier APFS MacOS The process normally takes a minute or two to complete. When the process is complete, you’ll see the following message: “Finished APFS operation on identifier.” The SSD is now formatted as APFS and is ready to use.