You could do this same basic setup. A 5 pin SPST relay doesn't care whether you are switching from the ground or power side. All your switch is doing is completing a circuit which allows the relay to trigger the electromagnetic coil inside (that completes the circuit to power your load). The coil has a 12v pin (85) and a ground pin (86) for the electromagnetic coil. Make one side always connected and the other switched - if you want to trigger off ground (low side switch), wire 85 direct to a power source and put your switch in the wire between 86 and your ground point. If you were doing a high side switch, you'd put your switch on the 12v side (85). It would be better if you understand what is going on not just try to copy someone else's setup without understanding it, not least of which for future troubleshooting.
And those crimp over taps are horrible, they often end up breaking multiple strands of wire due to their design. If you really have to use something that grabs signal off another wire, look into Posi-taps. They're not an ideal way, but they are a lot better.