Cant apply custom themes

hello everyone, Im using the latest steam version on linux mint. When i try to apply a downloaded theme i get an error: “Error loading /(the path to the theme)/sheet.png file”. I checked, the file is there and i can open it. Furthermore the theme worked when i used it on windows 10, even on the same aseprite version I believe. Here’s the theme btw Aseprite 95 Theme by Kacper Woźniak (non of them work).