Can a shared account post to Teams without using a license?

Hi,

We have an Events Committee at work and they plan all of our events in the office.  They want to be able to post event news and updates to Teams but don't want to post as themselves.  They requested we setup an "Events" account for them to use to post instead.  We thought about also doing this with an "IT" account to post things as the department instead of as individuals.

We already have a Shared Mailbox for Events as that doesn't require a license.  Is there a way I can create an Events ID that they could use only for posting to Teams?  I don't want to have to assign an E3 license to them just for this.

I see there is a Teams Trial license option in the admin center but I'm not sure what that allows access to so I don't know if I could use that as an option.

If anyone knows if/how we can do this, please let me know.

Thanks!