I have the note 10+ and got the banner registered and downloaded it and it's running good so far. Will form an exact full opinion later on tonight and then after a few days of use but so far everything is working for me
The OneUI/Android 10 Beta program is for unlocked AND unbranded devices right now, as far as I know. I have the N975U1. So the person who said that they have the U1 variant, the download is working for me. And the other person asking what to do after registering: go to Settings -> Software Updates -> Check for Updates (may say something similar here) and you should begin downloading the update.