Glad you got it up and running. I run a similar set up but with different gear - A Stages power meter connected to a Tacx Vortex Smart trainer.
In 2017 I had this ultimately ego shattering idea of running them side by side and to my horror, despair and impending depression, discovered that 250W on the Vortex was 200W on the Stages power meter.
Now I run the Stages as the power source, but it can take up to 20secs for the trainer to adjust to a new power target in ERG mode which is especially noticeable during workouts and shorter intervals. Sometimes 20 seconds of a 30 second interval will have gone before the trainer is able to match the power
Unfortunately none of the big reviewers test how quick power matching is across various trainers, so I don’t think manufacturers will ever look to improve the situation.