Anchor Links in The Menu

One-Page Site Option

You have the option to setup your site as a traditional multi page site, or as a one-page site. In the one-page style, you can still include links to other pages as well, such as the blog.

If you'd like your site to be One Page style, when building your site just add all of your widgets and content onto one page. For each section you can use the Elementor widget ID option, or the Anchor link widget to add your anchors. You can use any text you like, without spaces. For example: aboutus

Once you have that in place, you can create your navigation Menu under Appearance > Menus

On the left side, click Links, and input the URL to your page, including you anchor with a hashtag before it, ie: http://www.yourdomain.com/#aboutus

The Link Text field is for the text you'd like to show up as the link, ie: About Us

Once all your links are added, go to the top and click Screen Options. Ensure the box is checked for CSS Classes.

In each of your one-page links, click the down arrow next to Custom and insert the class 'th-anchor'

Elementor has a video showing how to use the Anchor Link widget option:
https://docs.elementor.com/article/62-menu-anchor