A published Mando help center is open to search engines by default. There is no SEO setting to turn on. When pages are missing from results, it is almost always one of the following.
Check the basics first
The help center is switched on. While it is off, search engines are told not to crawl the site and its sitemap is served empty.
The articles are published. A draft is absent from the sitemap and its address returns a not found page, so there is nothing to index.
Enough time has passed. A new site takes days to weeks to appear in results, and nothing in Mando changes that part.
Submit your sitemap
Your site publishes a sitemap at /sitemap.xml on whichever address it serves on. It lists the home page, every collection and every published article, and it updates itself as you publish. Add that address in Google Search Console and request indexing for the pages that matter most.
If you connected a custom domain
Search for your custom domain, not the old Mando address. Once a custom domain is connected, the Mando address is intentionally closed to crawlers and its sitemap is emptied, so the same articles never compete against themselves. Only your domain should ever appear in results.
There is no separate verification step for indexing. A connected domain serving your site is enough.
Expected behaviour that is not a fault
The search page is not indexed. Your site search results page is excluded on purpose, because search result pages carry no value in Google.
An article you opened before publishing still shows not found. That address can keep serving the cached not found page for a while. Add ?cb=1 to the end of the address, confirm it loads, then request indexing again.
Old links keep working after a title change. Article addresses stay valid when you rename an article, so a rename never costs you a ranked page.