This is where you must be extremely careful. Because Eaglercraft is popular among students trying to bypass school firewalls, many malicious websites offer fake "eaglercraft download file" links that contain viruses, adware, or spyware. Never download a file that claims to be a .exe or .msi for Eaglercraft. The official safe file is always an .html file or a .zip containing an .html file.
Search for "Eaglercraft Launcher" on GitHub. Ensure the repository is active and has good ratings. Download the .jar file and run it with java -jar EaglercraftLauncher.jar . eaglercraft download file