I need Skype to join calls with an outside vendor
You do not need to install Skype in order to join Skype calls. You can do one of two things:
A. Just the Skype meeting using your browser. Detailed instructions here: https://support.office.com/en-us/article/join-a-skype-for-business-meeting-with-skype-meetings-app-skype-for-business-web-app-4828ad18-ed21-422a-a870-94d676d4b72a
B. Join the meeting using the dial-in info included in every invite (if you don't need video or screen sharing)
If you wish to host video conferences, please use Zoom which is our current standard. You can request a Pro account for Zoom at the Helpdesk if your meeting needs to be over 45 min long.