I’ve now tried the download version. Finished after about 4 hours — a bit slower than before, but I was distracted by streams and emails.
The crash didn’t occur again. The rest worked fine, just like in the browser version.
However, I forgot to mention a minor issue I encountered a few times in both versions:
Sometimes, when exiting through the portal, I would glitch outside the cube and fall down to the station. This usually happened when the portal wall was already fully exposed, and I was standing on a white filler block positioned exactly one block away from the portal. From there, I either stepped or sprinted directly toward the portal. At the moment I touched it — when the teleport should trigger — I instead clipped out of the cube and fell.
If there’s enough time left during the fall, and you then jump further down from the station or passing it while falling, it counts as a completed level. Otherwise, you get the fail screen.
It doesn’t happen often, and I haven’t found a reliable way to trigger it, but it has occurred multiple times.