Go to Settings → Security → Unknown Sources and toggle it ON.
Game Guardian is a powerful tool. Using it in (PUBG, Free Fire, COD Mobile, Genshin Impact, etc.) will almost certainly result in a permanent ban . Many games also detect virtual spaces. Game Guardian 8.55.0 Apk Download
Apps downloaded from unofficial "piece" or third-party mirrors often contain bundled adware or viruses. Go to Settings → Security → Unknown Sources