I'm unable to check the "Sync Music" box in doubleTwist Sync.

There is a known issue where the Sync box is not selectable when Windows scaling is set to 200%.

We'll be resolving this in an upcoming release, but in the meantime you can do one of the following:

• Try temporarily switching to 125% or 100% scaling, select the "Sync music" option, then switch back to your original scaling settings. Here's a 3rd party help page on how to change scaling in Windows:
  http://www.tenforums.com/tutorials/5990-dpi-scaling-level-displays-change-windows-10-a.html
• Alternatively, if you don't want to change your dpi settings, do the following steps:
  • Check the "Import new music and playlists" box
  • Press the Space key to uncheck it
  • Press Shift-Tab (press and hold the Shift key, then press the Tab key)
  • Press Space again and the "Sync music" box should now be checked