As a Google-translated version of Adamo.Haru said:
"The official said on the side of Aidan that because it is dealing with BUG, the game will be re-released after the third chapter (only the red line) is finished, and it should be released this month at the latest (right 【】)"
From my understanding, the game is just temporarily unavailable to download and the download button was replaced with "[T]HE GAME HAS ENCOUNTERED A SEVERE BUG AND IS CURRENTLY UNDER REPAIR. WE APOLOGIZE FOR ANY INCONVENIENCE CAUSED."
So hopefully the newer version will be available soon, as the older version won't run on my computer without it being in a virtual machine.