Actually, the workout text should guide you through the process.
At the end of the 3rd Interval, you take note of your final HR. In your case, 132bpm. To me, this sounds very low after 3mins of near-threshold, but I guess we’re all different.
At the end of the 3rd Interval you are prompted to sit up, stop pedaling and don’t talk. Just do nothing and let your HR drop back down. After 1min of doing nothing, take note of your 1min rested HR. In your case, 90bpm.
Then subtract your 1min rested HR from your final Interval 3 HR. In your case 132-90=42HRR. Bigger HRR = better.
If you do the test regularly, you can use it to track your HRR and use it as a go/no-go for tough workouts. Over time, you may also start to see changes in your final HR at the end of each interval, which would suggest changes in fitness level.
If you want to do a deeper dive, then there are more resources out there