corrupt download / content not available so neither update nor reinstallation finishes

Hi,

my main comp has taken a bath from my cat, and is drying out right now, and the next days. Figured I can play my fave games via steam on my MacBook Air (2017), running High Sierra, i.e. OSX 10.13 I never had a problem doing that before. The update of DST did not install though, it stopped after 3.7MB, saying download corrupt. The usual checks, enough space is there, and then some, whole machine shut down and reopened, same with router. My friend google suggested to use big screen steam, which I did, but no dice. There was a new error though, which says content not available, or at one time servers not available. After a few hours, I uninstalled the game, and reinstallation now stops at 2.4GB with the same error messages, first content not available, now corrupt download again. All other steam games work, also all downloads of other games worked. I followed all recommendations found on Klei, and steam servers. No firewall issues, no programs running in the background, security turned off, and on, scanned for malware, etc. Anything else I can try?