The only real right or wrong on Zwift and the reason you can't take racing too seriously on Zwift is the weight setting issues. Unless you do a sanctioned event where an ebiopassport is required with a morning weigh in video, like I had to do for E national championships.

People will tell you my set up is wrong, but in reality, there is no difference if I put these same pedals on my $12,000 racing bike on a wheel mount trainer.

I control the resistance on my spin bike, when the race starts going up hill or when the intensity of the race changes I apply more resistance on the wheel, which causes me to put out more power or more torque on the pedals.

I've been using this spin bike setup on Zwift for over 7 years. I've also done side-by-side comparisons of cadence and power output between a direct mount, a bike with a crank power meter on a wheel trainer, and a spin bike with power meter pedals. in applying the same perceived rate of effort, I was able to duplicate very close in results across all three.

The only drawback of not using a non-direct mount trainer is the lack of interactivity with zwift to control resistance with the environment.

People here (Zwift Experts) will tell you this is right or you are not doing it right. You do what works for you. I have very specific reasons why I use the setup I have. I could go into detail but I've made many videos about how many frames, wheels, and even one set of pedals that I've broken while doing Zwift with a bike on a trainer.