Access to Network UNC path and UTM 9

Hey Nick KEY, 

Thank you for reaching out to the community, may we know how two sites A and B are connected, are you using IPsec between this two sites ? 

I am really not sure how is both sites connected, how can I know it? What I know, is, that I can access from site A to the server in site B with UNC path.

How can I see where the setting is for access? 

Well, if both the sites have an IPsec connectivity then you'll be able to access with the UNC if proper rules are configured. 
That's why I was asking you the connectivity means between the two sites...
Do you have an access to both the sites to validate the connectivity ? 

Yes I have access to both sites with web browser. How can I determine how both sites are connected?

Can you check for Site-to-site VPN on web-admin ? OR are from interface if sites have MPLS connectivity ?

I see under site-to-site VPN some Connections and some policy to location B.

I see under site-to-site VPN some Connections and some policy to location B.

Then from location A can you check the connectivity to Site B local resources whether you are able to ping or not ? 
If not then check what are the resources shared between site A and site B ?