jordanjay29 ahh right! Updated:
'url' => 'https://xxxxxxxx.xyz/discuss',
Now it's working.
So I understand, I don't need to reinstall whole forum, just moving files to sub-directory and updating URL in config.php is enough in order to run forum without any glitches? Just double-checking as I saw in other topics people were messing with their NGINX/APACHE configs so I wonder.