Thunderbolt 3 to Dual HDMI Adapter not working

[mbpmpb17]

So I bought a startec Thunderbolt 3 to Dual HDMI Adapter- 4K 60Hz.

I also bought 2 DP to HDMI cables, and when I plug both monitors into the thunderbolt 3 adapter, nothing appears on the monitors.

Do I have to configure anything on my laptop to accept dual monitors?

 

[PROFESS0R]

Make certain you are connected to the 40gb/s thunderbolt 3 output, and that nothing else other than power is connected to the thunderbolt 3 output on the same side. I use this exact setup and it works fine.

 

[Alameda]

Make certain you are connected to the 40gb/s thunderbolt 3 output, and that nothing else other than power is connected to the thunderbolt 3 output on the same side. I use this exact setup and it works fine.

Which output is the 40 Gb/s output?