The installer is programmed to use with Windows or Mac. I know that Steam Deck is linux. Zygor had a linux client and that wasn’t official, and chances are that the unofficial client would error out today. I know this because I saw a thread about this a long time ago. There has never been an official linux client for Dugi Guides, so I am not sure what else I can say or point you in the right direction. Normally I’d point to Linux Wine but, I doubt there would be a script created for DugiGuidesInstaller, as there would be a few to choose from for World of Warcraft.
I am sorry that I am not that helpful.
You could somehow get World of Warcraft on to the Steam Deck and then download the .zip files, place the DugisGuideViewerZ in to the AddOns folder, you can do this with any other addon.
Here is a youtube guide on how to get World of Warcraft on Steam Deck (World Of Warcraft On Steam Deck! COMPLETE Setup Guide With Controller Support) – I hope this helps