I try to use BToE PC Pairing as login option first time.
I installed BToE on my machine. I can login with it but after that I get info:
Authentication failed. Re-enter the password to access Exchange services.
UC Software Version 184.108.40.20646
Updater Version 220.127.116.1140
What's your infrastructure look like? Skype for Business and Exchange both on-premises, or Exchange Online? Have you checked that your Exchange Autodiscover records are correct?