Can I only build Android apps on a Windows operating system?

I'm just getting started with the new DPS beta trial, I'm following the 'getting started videos' and have got to the point where I am downloading the DPS Signing tool. However, when I launch the tool, I can only sign Android applications. Whereas in the video, there is an option to choose Android or iOS. Is this because I am working in Windows?

Additionally I have registered as an Apple Developer so that I can create certificates for iOS applications.