Hello,
1) Yes, you can just ignore that message.
Elementor developers do not allow to include Pro version of plugin with any theme, they do not have special license for these purposes, unfortunately. We contacted them about this long time ago.
2) If you want to import demo content created by the Elementor and edit it using Elementor you need to import demos from this tab only https://prnt.sc/t8h37b You can import any other demo but you won’t be able to edit existing page/static block content using Elementor because it was created using WPBakery, it’s not allowed to mix builders within the same page/static block. In this case, you will need to create your page from scratch using the Elementor builder.
Regards