Just throwing in my 2 cents here, I was able to use just the conditional for acf pro and it works on wp installs with acf regular and pro.
So, in my plugin file I have:
/* Checks to see if “is_plugin_active” function exists and if not load the php file that includes that function */
if ( ! function_exists( ‘is_plugin_active’ ) ) {
include_once( ABSPATH . ‘wp-admin/includes/plugin.php’ );
}
/* Checks to see if the acf pro plugin is activated */
if ( !is_plugin_active(‘advanced-custom-fields-pro/acf.php’) ) {
/* load the plugin and anything else you want to do */
}
and if my install already has acf regular, my needed pro features work, and if it has acf pro, it doesn’t load and everything works as well.