Use these instructions to turn your daily wallpaper into a native macOS screensaver.
Open the Basalt app and go to Settings. Under the Screensaver section, toggle on "Sync wallpaper to screensaver".
In the same settings section, click the "Reveal in Finder" button. A Finder window will open showing the Screensaver folder. Keep this window open—you'll need it in a moment.
Open System Settings and click on Wallpaper in the sidebar. Then, click the Screen Saver button to view your screensaver formatting options.
In the settings window, scroll to the bottom and click the Photos option.
Scroll back to the top and click Options. Then select Choose Folder... and pick the Screensaver folder you revealed in Step 2.
Your screensaver is now linked. Whenever Basalt updates your daily wallpaper, your screensaver will automatically update to match.