“Work with apps” feature in ChatGPT app doesn’t appears

Hello everyone! I have a question about the ChatGPT app for macOS: It's impossible for me to activate "Work with apps", I don't have the button at the bottom of the window and there's nothing in the app settings either. I'm a free user, but I don't get the impression that the feature is reserved for premium customers... I'm of course on the latest version of the app and macOS is also up to date on 15.3. Any ideas?