The game doesn't have cloud saves due to world sizes exceeding reasonable cloud storage limits. A world I've played on for a couple of months has reached 4GB of size, and there are even larger worlds, from players who love to build. Currently, Staxel has 1000MB of cloud storage: not nearly enough for a single world with good progress.
Though that issue has mostly been solved with the release of Staxel CE, only supporting cloud saves for one version of the game would likely be confusing for many. It's best to warn users that worlds must be backed up manually, using their cloud storage provider of choice.

• World saves for the original, Windows-only version of Staxel are located in the game's LocalContent folder. You can find this by right-clicking the game in your Steam library, hovering over Manage, and clicking on Browse local files.
  
• World saves for Staxel CE are located in the "My Documents" folder, as specified by the operating system.

I understand, but it's tiring to transfer saves from one computer to another. This is the downside of this game. Apart from that, the game is fun and I like playing it.