Dual External Monitors on a (late) 2017 MacBook Pro
Your problem is that you have chosen a USB-C hub - this means that MST is a requirement for supporting dual displays in a non-mirrored configuration. MST is not supported on macOS, but will work if you run Windows.

In order to get dual displays working, you'll need to either: (a) connect each monitor seperately to the two Thunderbolt ports on the Mac - directly or through your hub, or (b) get a Thunderbolt 3 hub/dock with dual display capability.

Such a Thunderbolt 3 dock could be for example the OWC Thunderbolt 3 Dock. With that dock you would need to connect your two monitors to the dock like this:

Monitor A: Connected to mini-DisplayPort port
  Monitor B: Connected to daisy-chain Thunderbolt 3 port

Note that you'll need cables that match the inputs your monitors support. That could be for example a mini-DisplayPort to DisplayPort and a Thunderbolt 3/USB-C to HDMI cable.

The OWC dock is just one option - many other docks are available from various vendors at various price points.