Hi,I'm trying to figure out how to get the ui 2 beta
What firmware r u running? To get the beta option to appear u have to be running SM-N960U1 firmware first then there are 2 other steps
The last 2 steps are delete the play store samsung members and download one on apkmirror run it, delete it and reinstall members app from play store open it and u shuld see the beta invite option
Then sign up and then try updating your firmware in settings>system update, it should be there for you.
The final, stable should be pushed soon anyway
Ps all the betas have been stable especially if you wipe everything and start new with U1 firmware which is the only way u will see the invite, hope this all helps