Custom Post Types templates not loaded

Hi!

I want to use a custom template for a specific post type.
Post Type: ova
Template: single-ova.php
Directory: /plugins/accelerated-mobile-pages/templates/design-manager/design-3

I read into https://ampforwp.com/tutorials/article/create-custom-template-post-type-taaxonomy-amp-theme-framework/ but it doesn’t work for me.

Or where I need to put the single.php file?

Regards,

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