Download the DMG, open it, and drag Douvo.app to Applications.
Browser and Homebrew downloads can be tagged with Gatekeeper quarantine. If macOS blocks first launch or says the app is from an unidentified developer, trust the installed app once:
xattr -dr com.apple.quarantine /Applications/Douvo.app
open /Applications/Douvo.appMore detail: README — Install · SPARKLE.md