Microsoft yesterday released a new cumulative update for Skype for Business Server 2015.
From the KB this look to resolve an issue for Windows 10 users who try and join meetings via the Skype for Business Web App using Edge browser.
As Windows 10 is growing and growing i would recommend deploying this CU to your servers to ensure everyone can get in meetings if they dont have Lync / sfb.
If you cant apply the CU just yet there is a workaround where you have you manually append ?SL=1 to the end of the meeting url and the meeting will appear correctly.
More details are below.
SfB Server CU download