I use Vortex.
Tyre to 7 bar
Tacx utility tool on phone/ipad select calibration. Pedal to 32 kph then stop as required by the app. It should show a red line in the middle of the green bar. Adjust the resistance on the tyre until you get this.
Zwift doesn’t have any in app resistance check
Trainer road. Uncheck all the devices except Ant plus trainer. Click on Ant trainer and calibrate. Power match auto.
You should note that the power change is part of an algorithm so will feel slightly different on both these apps. I find Zwift and Trainer road to give about the same power read out and feel. Power comes on in both fine.
I don’t use the Tacx app as its sessions are pants but they are improving and now multiplayer is free. Competition must be hurting them.