save .psdt to creative cloud

I don't think that's possible. The cloud docs have their own unique file extension, so you can't save a template file that has it's own unique extension. Another issue would be how cloud docs save. They auto save in the background or when you close the file. That would overwrite your template file, usless you actually did a manual save. Cloud docs were designed to be worked on separate devices where updates were more or less automatic" do a little work on a laptop,  and the changes show up on an iPad, etc.