iHomefinder Optima Express plugin compatibility means that the theme works well if you iHomefinder Optima Express. The theme will not return any errors just by using these extra options. IDX plugins are Optional and they are not required for the theme to be installed and used.
About iHomefinder Optima Express plugin compatibility
How IDX Plugins work: If you install one of the IDX plugins, they will work with the theme, without conflicts. BUT the properties added through the plugin can be managed only with plugin features, options. They will NOT be used with the theme options. The properties from IDX are managed in a different database and the theme cannot access those properties (the plugin developers do not offer such access). So you use the plugin as it is, with its own design and features.
Wp Residence has the option Use Optima Express plugin. It can be found in Theme Options > MLS – IDX – RESO.
You must install separately iHomefinder Optima Express IDX plugin.
Note: If you do not have iHomefinder activated disable this option. If you activate support for IHOME FINDER plugin without the plugin being activated. then there could be conflicts (especially with dropdowns and tabs)
Mls Import plugin compatibility
For a seamless MLS integration, your properties must be imported into the theme database. Such a solution is available with MLS Import, a 3rd party plugin publishes and automatically synchronizes listings directly with your MLS. Check more info and demos on their website – https://mlsimport.com/. Video for MLS Import https://www.youtube.com/watch?v=ocaBl0zs-FU