I’m far from expert and others might well contradict me, but I’d say what you’re seeing is normal. At 55w, unless you weigh almost nothing you’re going to be moving very slowly on the flat… if there’s an incline (which you’ll see in the thumbnail map) you’ll be crawling along. Don’t worry about it - it’s quite demoralising seeing them fly by, but the important thing is to maintain your power and follow the workout.
On the spinning out I suspect you’re at the lower threshold is the Atom’s resistance; the resistance decreases as cadence increases to maintain a set power - that is, you have to pedal harder if you’re pedalling slower to produce a given power output than if you’re pedalling fast. At 95rpm and 55w you’re probably spinning out as it says. 75w should be better, but you can always reduce the cadence a little until it starts to give a little resistance. Your FTP results won’t be affected that much by it and you’ll have a better experience.