Use SWITCHvideoconf on a desktop computer without admin rights
Even in the case when you have no access to some desktop computer which you could install some programme on, you are still able to participate as a guest, very much the same as if you participated from an iPad or iPhone.
However, you must be able to obtain an invitation link. Clicking on that link sends you to the page below. Accept and download the plugin, then run it (this you can normally still do even though you may not have admin rights).
After successful completion, you will be asked to identify i.e. label yourself accordingly before entering the virtual room and then to enter the PIN for the room. You will now see and hear your colleagues.