Newbie really struggling and need some help please

[DamoT]

I purchased a second hand AtGames Legends Virtual Pinball + VIBS + Backglass Board and want to connect it to my PC to get the additional tables shown to me by the person I bought it from. 

I have a laptop dedicated for the job which is a Dell Precision M6700. It only had one HDMI port and a Display Port so I connected the two cables from the Pinball to this. 
I could only get the main Laptop Screen and the main Pinball screen to show properly in Windows. The 3rd screen would show up but when you click "Identify" it only shows 1+2 not the 3rd (Backglass).

I bought a port replicator (Docking Station) as this had 2 Display ports and god adapters to HDMI but same issue. 

If I unplug the cable for the main pinball screen then the 3rd one springs into life.

When all connected the backglass just shows a cycle of multiple colors. 

What am I doing wrong? Will I need to get a new computer to do this and if so, what do people recommend without spending a fortune. 

Thanks in advance.
If you need any pictures, please let me know.