itch.io

No, I doubt there is since there are cheat programs that can unlock Steam achievements for any game

You can just put the files from here to the Steam folder and it will work.

You didn't add the DLC files correctly. If done correctly, there should now be Z_DLC files in your game folder's /www/data/ folder.

Try redownloading the latest version

Try clearing your browser cache and restarting your PC

No

There are currently no plans for further DLCs.

As written on the page, this is a DLC, not a standalone game. You need the base game, Karryn's Prison. Once you have the base game, you follow the instructions in the Read Me.txt of the DLC folder to add the DLC game files into the base game's folder.

There are no plans for a demo

No

Yup

I guess the download server is acting up. Try using 7zip to unpack, and then use one of the random file in the /www/audio/bgm/ folder to copy and rename into 03_Cathedral if the 03_Cathedral file is still corrupted.

No, because adding animations is not a simple task, and this is an already finished game by the developer with no plans to add animations

No

Maybe after Itch.io increases my file size upload limit, but it's going to be an experimental android build that I've not tested so no guarantees if it will work or not on Android