Hi Jamie,
Sorry for the inconvenience. To narrow down the issue, may I double confirm the situation and collect the following information first:
1. Are there any errors occurred? If yes, could you capture a screenshot of the error and post here for further research?
2. Could you refer to the steps below and check whether the Lync online license has been assigned?
Sign into Office 365 with admin account -> "User & Groups" -> Double-click your user account -> "licenses", then you can check whether the Lync online license has been selected.
3. What's the version of your Lync client?
Thanks,
Aaron Yuan