Get posts average star rating
I feel little stupid because I couldn't find an answer to this question through the search function. Anyway!
How can I retrieve the average star rating of a post?
Please navigate to Dashboard > Comments > Settings > Comment List admin page, make sure the "After Content" checkbox is checked in the "Display Ratings" section. Save, delete all caches and check again.
Don't forget to press CTRL + F5(twice) in the frontend before checking.
Thank you for clarifying.
Here is the postmeta key you should use:
Please note, the Meta Key doesn't return the post average count. The key includes the count of each rating(5/4/3/5...). You should count the average value of each post manually to get the star rating of the post.