Our Partner Microsoft has not validated UC Software 6.0.0 or 6.1.0 via their 3PIP program. This means these Software versions will not be able to sign in to Skype for Business Online.
A working firmware is 5.9.3 which is available and can be used.
Please ensure to provide some feedback if this reply has helped you so other users can profit from your experience.
Notice: This community forum is not an official Poly support resource, thus responses from Poly employees, partners, and customers alike are best-effort in attempts to share learned knowledge. If you need immediate and/or official assistance please open a service ticket through your proper support channels. Please also ensure you always check the VoIP , Video Endpoint , Skype for Business , PSTN or RPM FAQ's