Since the old link doesn't work anymore, here is the new link: https://mixels.fandom.com/wiki/User_blog:BENSEGHIR777/How_to_install_Calling_All_Mixels_or_Mixels_Rush_using_a_single_APK_file

Follow the Instructions on the website on how to install the game correctly. Don't worry, everything you need from this website is safe to download.