I am trying to install XProtect Smart Client 2017 R3 on Windows 7 Ultimate system. Client fails to install. Please suggest which client I need to download in order to install it on Windows 7.

As this does not pertain to development but to a general situation you will most likely get better help from the partners active in the Support Community - https://force.milestonesys.com/support/MccSupportCommunity