Legitimate software rarely includes "Downloader" in the actual filename of a disk image ( .dmg ). This usually indicates a stub installer that, once opened, downloads and installs additional (often malicious) payloads.
"Spring Blossom 2020" is designed to look like a screensaver, wallpaper pack, or harmless utility. spring blossom 2020 - Downloader.dmg
This is a macOS disk image. If you are on a Windows or Android device, this file cannot run, but its presence suggests a targeted attempt at Mac systems. Associated Risks this file cannot run