You can download the demo version for free or purchase the full version on the game’s itch.io page: https://splixun.itch.io/mazevil.
About install and updates : If you install the game with the itch app, you have nothing to do, installation and updates will be done automatically. For others, unzip the downloaded file wherever you want. The game will warn you when an update is available. Access your library to download the new version or follow the download link given by itch.io in the mail sent during your purchase …
Have fun =)