We install cameras on many tenant properties. We usually install in public spaces such as the exterior and hallways and all tenants are aware of the cameras. I have had none that objected in the many installs we have done. Most really wanted the extra security and the owners told them they would supply them footage in an incident.

Best to explain to the existing tenants that you will be installing it for safety and all new tenants have it written into the lease that there is 24-hour surveillance in public areas.

We have installed them with, tenant internet, dedicated internet, and local wireless router depending on budget.
In the cases of us using the tenant internet they had good relations with the tenant and worked out some type of deal. Obviously good relations can turn bad but that between the owner and the tenant to work out, nothing to do with you as the installer. Just explain to them that if they decides to change over in the future it will be an additional charge. There were a few were we went back and changed to another tenant, dedicated or a local router. But this was a while after mostly because the tenant had moved.

At a few other locations the owner had a property manger that lived on site and used their internet. If that is not the case, dedicated internet is the most expensive option if he wants to see and retrieve information from home/away and the local router option is a good cheap alternative to being able to sit in a car and review footage.
We usually install the systems in a lock box or locked closet where they can run us a dedicated circuit from the house meter.