You are not permitted to use the Software in connection with the provision of any commercial services which include processing or transferring the data of or for other persons or entities (“Data”), including cloud computing and “Software as a Service” solutions, providing storage capacities for Data; transmitting, routing of or providing connection to Data, or providing information search tool services
As you want to use it in a commercial environment, the answer to your question if you are allowed to use the free version seems to me to be no.
As there is a IT department...
You do not (or at least shouldn't) want the users to make changes to settings and such.
I advise to use a centralized manageable system that the users can't override.
As there is no server, I advise to use the cloud version for businesses from avast (or another company)
If you give the 50 users control, a IT department is a waste of money