If there is a "Manual Install" or "TNT" script in the folder, run it first if the app fails to open due to "damaged" file errors (a common macOS Gatekeeper issue).
Always ensure you are downloading from a reputable mirror site. Malicious actors sometimes re-package TNT releases with unwanted "extras." Download Tunes Kit Audio Converter [TNT] dmg
Locate the TunesKit_Audio_Converter_[TNT].dmg from your preferred source. Mount: Double-click the .dmg file to open it. If there is a "Manual Install" or "TNT"