Thanks for the quick response MrDaleSmith.
So I did install the module via composer by running the 'composer require drupal/patreon' from the site's root.
The below tells me everything should be installed correctly:
Lock file operations: 2 installs, 0 updates, 0 removals
- Locking drupal/patreon (4.0.0)
- Locking patreon/patreon (1.0.0)
Afterward, I registered the app on the Patreon site to get the key and the secret and put https://MYSITE/patreon/oauth as the endpoint.
Then, I put the key and the secret in admin/config/services/patreon/settings.
Finally, I pressed "Save Configuration" which brings the Patreon permissions page where I just click "Allow" and it redirects me to the endpoint above with 2 query params 'code' and 'state'.
The /patreon/oauth page returns as 404 and I see the error in the Drupal logs.
The same happens on 2 two separate sites I am running with Drupal Version 9.5.7 PHP 8.1.14.
Not sure it matters, but the composer version is 2.5.5
Thanks for your help!