Troubles with Sitemap updating from Yoast to RankMath

I recently transferred from Yoast (deactivated) to RankMath (activated). What I am trying to do is solve for why, when I click the Sitemap URL under the RankMath tab, it navigates to an older sitemap from the deactivated plugin: “Generated by YoastSEO, this is an XML Sitemap, meant for consumption by search engines.” (see sensitive data)

When I go to RankMath’s Sitemap settings, I get an error message: “Since you are using NGINX, add this code to your NGINX configuration file if your Sitemap pages are not loading or you can ask your hosting support to add it. Click here to see the code.” I am not sure if this is the cause of the Sitemap problem or not.

I ran the Site Health app laid out in the RankMath SiteMap Support Guide and it found no issues.

Regarding the NGINX error, even though I have virtually no idea what I’m doing, I read the guide provided by the link for the RankMath Sitemap Settings error message. It says, “The main config file can only be seen or edited if you’re using an admin user on a Dedicated server.” So, I went to my hosting configurations, it says, “For the tech-savvy, manage your database with phpMyAdmin and run a wide range of operations with MySQL.” There is an option to open the phpMyAdmin database there, but I’m not even sure I’m on the right track. Am I supposed to open this up and insert the code from the error message?

Any help you can offer to update my SiteMap, because I suspect this is the reason my website is not hitting the search engines, would be fantastic.