Lync - Now known as Skype for Business O365

So I went through the setup instructions for skype for business.

https://support.office.com/en-us/article/Set-up-your-network-for-Skype-for-Business-Online-81fa5e16-...

All DNS entries and firewall entries are in place. We currently have about 30 users who are using O365 ProPlusand another 90 users who are just using Email service(Exchange Online Plan 1).

I want to enable the Skype for business for the 30 users that do have the O365 product however when i download their mobileapp and attempt to sign in on my mobile device i receive "The account you used to sign in is not provisioned for "skype for business service". Where is this provisioned at? With the desktop install of O365 "Skype for business" was installed and I tried using my credentials with no avail. What am I missing?

I see no options in the O365 portal as an administrator for...