When you download the file, macOS High Sierra will likely block it because the developer certificate is old. Here is how to open it safely:
If you experience performance issues with uTorrent on older hardware, many users recommend these lightweight alternatives for High Sierra: Transmission Download Utorrent For Mac High Sierra 10.13.6
Do not use third-party "download aggregators" that bundle adware. The safest legacy archive is hosted on the official FTP mirror (no longer linked from the main site, but still active). When you download the file, macOS High Sierra