DuoPlus can be used directly in the browser, including on mobile browsers. Just access https://my.duoplus.net with a browser. If you need a desktop client, you can also install it.
Latest client release page: https://www.duoplus.net/download/
System Requirements: macOS 11 or later, 64-bit operating system
Download Links:
Download link: DuoPlus for Google Play
Download link: DuoPlus for APK