I checked using the current version of the itch.io app and I don't see any issues. To be clear, there is only one download, and it is marked as supporting both Windows and Linux:
It contains the following binaries:
- Distributrains32 - For 32-bit Linux (x86)
- Distributrains64 - For 64-bit Linux (amd64)
- Distributrains32.exe - For 32-bit Windows (x86)
- Distributrains64.exe - For 64-bit Windows (amd64)
If you are on a supported platform and the download doesn't show up then you might need to talk to itch.io support.