Wait? So you can upload to Amazon or Google but nowhere else? Like to your own servers, for example?
We want to have more ways to do this though. We were close to adding SFTP support, but didn't get round to it. Another method could be to implement our own server, but we're trying to keep it simple for now. I'd be curious to hear your feedback here: https://github.com/replicate/replicate/issues/366