After a run of the first lesson, I got a Cpm of 220 with 1 error after a 5 minute test. I was rated 86 points.

Per the comparison table window, this result should have been rated for 110 points, not 86.

The score is calculated as follows:
((Strokes - (20 * Errors)) / Duration) * 0.4
according to your data:
((5 * 220) - (20 * 1)) / 5) * 0,4 = 86,4

We know about some wrong samples in the comparison table - we will correct this soon.

All the best from Berlin,
Your Tipp10 Team