Restrict Content Pro is designed to work well with any theme that follows WordPress coding standards and recommendations. The plugin comes with minimal styling in order to let your theme's design shine through.
Most (if not all) themes in the WordPress.org theme repository should work well with Restrict Content Pro.
The one thing that may sometimes cause issues is page builders since some of them have their own method of displaying content. This is only a problem with a few page builders though and many will work with Restrict Content Pro just fine. If you encounter any issues with your page builder or have any questions about the one you're using, please contact support and we'll be happy to assist you.
As a general rule, Restrict Content Pro should be able to protect any content that's inserted into the built-in WordPress post editor. If you're adding content somewhere else (via a page builder or custom field) then RCP may not have access to protect it automatically. However, we do have alternative methods for restricting content that may work instead, such as our [restrict] shortcode or inserting custom code to restrict content in template files.
If you have questions about a specific theme, feel free to get in touch with us through our support page and we'll do our best to help!