FYI: EWS might depend on this folder and we have seen cases where SFB client had 15 minutes delay to recover EWS errors. You need to make sure that this folder exist or to disable it with policy. One of the ways to create this folder is to use Lync 2013 RTM client.
https://support.microsoft.com/en-us/help/4015948/deprecation-of-skype-for-business-contacts-folder-in-outlook-and-outlo
