Use Elementor Pro for Guest Author archives:
(Version 3.20 and up)

Note: To use the free version of Elementor on single posts, you must Disable guest author archives in the plugin settings. This will disable guest author archives for all guest authors.    

1. Go to ‘Theme Builder’ in Elementor Templates.
2. Create a single template for the Guest Author post type
3. Drag a Elementor posts widget to the template, along with title and post navigation and any other elements you wish to add.
4. Open up the ‘Query’ panel in the posts widget settings and enter ‘guest_author_filter’ into the Query Id section. You may also enable pagination.
5. Other options besides the posts widget may be available via ‘Anywhere Elementor Pro‘