Edit Blog, Shop and Archive pages
Tutorials for WPKoi themes with template parts
Blog setup with site editor
If You want to edit the blog, shop or other archive pages, go to the site editor.
Basically You can't edit these pages with Elementor! They have different structure. Elementor Pro or another third party plugin could solve this. Or You can build a page with Elementor and use that as blog page.
Template parts
In the new generation WordPress themes the navigation editor moved to the site editor.
Go to Appearance-> Template Parts admin menu and select the template part with Your menu.
Choose the index for the blog page and archive for category pages.
You can find some extra layout, color and other options in the customizer at the Appearance-> Customize admin menu.