You must be allowed to install applications from unknown sources, as You install apk directly. If your built-in antivirus recognizes this package as suspicious - we need at least information about what kind of antivirus it is and what specific danger it detects.
This is strange, this does not happen on our devices. To install the game, you can temporarily turn off Google Play protection, but be careful with this and do not forget to turn it back on after installation.
