Note: This information only applies to users who have installed the Windows 10 Creators Update (version 1703).
Microsoft has made an update to Windows 10 that allows it to see multiple partitions on USB drives, including non-Windows format partitions. If you insert a USB drive with a partition for non-Windows files, such as the FTM USB Drive which has the Mac installation file on its own partition, you will see a warning message like the one shown below.
If you see this warning when using the FTM USB Drive, don't worry — there's no need to format the disk. All you need to do is click the Cancel button to close the warning whenever it appears. All of the files on the USB drive will be safe and you can proceed to install Family Tree Maker for Windows.
Important: If you click Format disk, the installation file for Mac will be lost.
After you click Cancel, a second warning message may appear — the Location is not available warning:
In this case, just click OK.
Then click Cancel once more when the first warning appears again. The warning will close, and you can continue with installation.