Currently the SpeedScriber app is only available for macOS although we do plan to support other platforms in the future.
However the SpeedScriber panel for Adobe Premiere Pro CC is cross-platform and available for macOS and Windows. By using a single SpeedScriber account, you could have one macOS system importing files (and editing if desired) and then multiple systems running Premiere Pro on Windows which can access that transcript data and add it to clips.
The administrator portal for seeing usage, buying minutes and changing default billing information is web-based at app.speedscriber.com