404 Error When Trying to Unlock Post /patreon-flow/

Hi

First of all thanks for the response!
Although I have mentioned that I’m using pretty permalinks in the form of “/post-name” I rechecked it to make sure. It is set so.

However,
The health section indicates that everything is great!? Probably minimum system requirements-wise. Because when I checked the most bottom panel there are some reports like these ->

Your site is using:

WP 5.5.1 with PHP 7.4.10
Patreon WordPress 1.6.8 with API v2

fetch_creator_info - API v2 Class - UUID some alphanumeric characters here - Response code: 401 Response :{“errors”:[{“code”:1,“code_name”:“Unauthorized”,“detail”:“The server could not verify that you are authorized to access the URL requested. You either supplied the wrong credentials (e.g. a bad password), or your browser doesn’t understand how to supply the credentials required.”,“id”:“some alphanumeric ID number here in original message”,“status”:“401”,“title”:“Unauthorized”}]}

I have played around with direct access / List Index settings on my server just to prevent,

  1. Hotlinking to files like mp3, jpg and so…
  2. Directory list indexing of such directories like (/wp-uploads… etc)

And these settings work as expected without problem.
Can it be about these settings? If yes, then how can I make sure I still have the above protection bu at the same time letting the Patreon WP runs smoothly?

Another thing, I’m not really good at all about server side things. Is this something related to a redirect problem?
Because as I’ve mentioned before, if I press the back button 1-2 times after getting 404 Error, the browser renders/loads a Patreon page where it says something like “become redwhitesound’s patron”. But first click of the button always gives 404 Error prior to that.

Thank you a lot!

EDIT: I should mention that I tried several fresh installs of the plugin with matching tokens and etc.