Error: No route was found matching

Is the plugin active now? Where did you go to cause that error to appear?

Oh, do you mean you can’t access the Settings page in the admin?

OK, that’s interesting.

Are you using the block editor (Gutenberg) or the classic editor? If the block editor, are you able to save changes to posts?

When you save the settings, what happens is a POST request is made to /wp-json/amp/v1/options?_locale=user. For some reason this is failing for you. The error you’re getting indicates that the WordPress REST API is responding to the request but it isn’t finding the route.

Do you by chance have any special rewrite rules, like in .htaccess or something?

What’s strange is that I can make a request to the REST API endpoint on your site and for me the route is being found, and it is responding as expected saying I don’t have permission:

$ curl -d '' https://worldincentivenetwork.com/wp-json/amp/v1/options?_locale=user
{"code":"amp_rest_cannot_manage_options","message":"Sorry, you are not allowed to manage options for the AMP plugin for WordPress.","data":{"status":401}}

I recommend opening the browser DevTools, going to the Network tab, and check the request that is made when you save the options. Is it going to expected location?

(Don’t share a screenshot that includes the x-wp-nonce.)