The internet is filled with deceptive ads and fake "setup.exe" files. Eaglercraft runs entirely in HTML and JavaScript.
While you may see "1.21" or "1.21.4" mentioned in community forums, these are typically not full ports. Here is the current landscape of available versions: eaglercraft 1.21 4 download
focuses on porting older versions like 1.5.2 and 1.8.8 to the web, recent community efforts have claimed to bring modern 1.21 features to the browser. Status of Eaglercraft 1.21.4 The internet is filled with deceptive ads and fake "setup