Mercurial isn't yet supported in the Windows version, however will be added very soon. The FAQ states "Due to time constraints, only Git is supported in the beta version. Mercurial support will be coming later in version 1.0."
Hope that helps
Atlassian Summit is an excellent opportunity for in-person support, training, and networking.Learn more
Supported Platforms macOS Windows To make using Sourcetree as simple yet powerful as possible we embed (bundle) dependencies such as Git, Git LFS, and Mercurial. We strive to keep these...
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
You're one step closer to meeting fellow Atlassian users at your local meet up. Learn more about AUGs