Hey macOS peeps! Some more news! ^^
So, for those encountering the 'Permissions' error, which seems to be consistent on BigSur, I am now able to present an alternative; the WebGL version! We now have a browser build of the game available and it has been confirmed to work on Mac computers that were unable to run the macOS downloadable build. While the experience of the WebGL version is marginally less-so than the downloadable version, it works!
There is additionally another potential solution, however it involves utilising Terminal to alter the game files, and we can not safely recommend this process, however, at your own discretion, you are able to search that fix yourself~ ^^
I apologise this isn't a proper fix to the build, but given my current facilities, this is the best solution I am able to provide~ I hope everyone is able to enjoy the game!! ^,,^