You need to connect motor wires to motor cables together. You can use soldering, but that is tedious and you need to secure the cables and connections anyway. A good solution to this is using terminal blocks, for example, like this.

However, connecting multistrand cables like this reliably to screw terminals is not trivial.

Getting all strands under a screw is difficult, and you don't want loose strands to cause shorts. Soldering the strands together is a bad idea, as the soft metal under the screw pressure will creep and the connection will get loose. Don't do that! A better way is to use ferrules. These are small metal sleeves that go over the wire end. You crimp them to the wires using a special tool.

 and   gives you   :-)

You can find the accessories for this here.