IT Services recommend you use Windows Defender if you are on a Windows 10 machine.
Why not try this link for help with Windows Defender and Windows 10
For Mac please use the instructions below
Open a new window and paste in the the following link https://www.sophos.com/en-us/products/free-tools/sophos-antivirus-for-mac-home-edition.aspx to go to the Sophos site.
Follow the steps to register and download the installer.
Open Downloaded File
Open downloaded file. Bring new window to front.
Open your Downloads folder. Your browser may have unzipped the download automatically, if not then double click on the zip file (normally called savosx_he_r.zip)