the post that you linked to is for a different brand and model. Remember the first rule of home automation: “the model number matters.” So the fact that it can be done with A zooz doesn’t necessarily mean it can be done with another brand.
In any case, You don’t use the traveler wire. And you don’t have the second master, the one in the auxiliary position, wired to the light, either. You just put it in so it has power and then you use it as a virtual three-way. The auxiliary will send a message to the hub and the hub will send a message to the Master. You can set this up using the “mirror” feature in smartlighting.
To be honest, I’m not sure if that wiring can be done with the GE model, but hopefully someone else will come along who will know.
Also note that if you do set it up this way, it will only be able to operate when the smartthings hub is operating.
One of the reasons that people will select the GE switches is because when you use the master and the normal auxiliary switch you do use a physical traveler wire and they will continue to work just fine even if your hub fails together. But a virtual three-way requires the hub to be working. So that’s just something to be aware of if you choose to use two masters.