It looks like you had already v4 installed on this machine. This is what installer complains about (not about version 3).
You may try looking for "B8DC6C33-ADF5-47EC-9116-705C0C8F408C" in registry - this is product code of DVBLink Server v4.
Server: Synology DS214Play, DVBSky S960CI Astra 28/23/19 (CanalDigitaal subscription), TeVii s660 Amos 4/Sirius, DVBLink TVSource 5.0.0
Clients: AsRock ION 330 Win7 with XBMC 13.1, Raspberry Pi with XBMC 13.1, Samsung DLNA TV, Samsung Galaxy S3, Nexus 7