Without ACF installed, none of the fields you add to your plugin will work. If the fields are only available in the pro version then those fields will not work without ACF pro installed. Your plugin will be dependent on ACF also being installed. You’ll need to build in checks to not call the ACF function if it is not installed. Or you can use ACF hooks where needed which will only be called if ACF is installed, for example acf/init instead of init
