Row 1 knit
Row 2 knit
Row 3 Purl
Row 4 (k 2tog) 3 times, (yo, k1) 6 times - and that is repeated across the row.
You begin with 90 stitches, and are supposed to end with 90 sts.
Based on what you provided above, you can't start and end with the same number of sts. The 3 k2tog will only decrease 3 stitches, while the 6 YOs will increase 6 sts. Thus, you will have a gain of three each time you do the repeat.
Either the K2tog has to be worked 6 times (to match the YOs or the YOs need to be only repeated 3 times (to match the k2tog)
Addendum: I checked the LionBrand website and row 4 above, as you have it, is incorrect. It should be...
Row 4 *[K2tog] 3 times, [yo, k 1] 6 times, [k2tog] 3 times; repeat from *.
Now you have (3 decreases, 6 increases and 3 decreases) per repeat. All is even!!