Catalina is the last OS where you can "Allow" the system extensions BlueStacks needs to run. Newer macOS versions (like Big Sur and beyond) made this much harder.
High RAM usage (minimum 4GB, recommended 8GB) can cause significant slowdowns on older Intel hardware. Kernel Panics: bluestacks mac catalina
If you already installed BlueStacks and it crashes or freezes, try these remedies before giving up. Catalina is the last OS where you can
Leftover files from Nox, Genymotion, or old BlueStacks builds will cause kernel panics. Use AppCleaner to drag every old emulator to the trash. bluestacks mac catalina