You will not be able to use the limited free version of Skype Meetings if your company already uses Office 365. You can try signing up for Skype Meetings using a different email address (go to https://go.skype.com/meetings.signup).
Or, contact your workplace technical support and ask them to give you access to Skype for Business, which includes the full version of Skype Meetings. If you are unable to get either, you can always use the consumer version of Skype for video calls.
