Hi @Mec 
I was able to just post to that subreddit with a new Reddit account, and am not having any errors with any other aspect of the node.
Have you also followed https://www.reddit.com/wiki/api/ and clicked “register”, and filled out the form? After making sure I had an app created at https://www.reddit.com/prefs/apps and submitting that form, I’ve no issues fully using the node.