right now we have no official support for Sync.com.
However, Boxcryptor works with almost every cloud provider.
As long as you have a folder which gets synchronized you can easily add this folder as a Boxcryptor Location.
Please have a look at this tutorial:
On mobile the situation is a little bit different, because we have to implement every provider by ourselves.
However, if Sync.com supports webDAV, you can add it with our mobile apps.
Sync.com is on our list of cloud providers which should be included, but I can neither say if nor when official support will be available.