The actual directions say:
"2nd row: Sl1. *K2tog. Do not slip sts off needle. K2togtbl into the same sts. Slip 2 sts off needle Cluster 2tog made. Rep from * to last st."
if I'm looking at the right pattern.
It's saying you should K2tog, but keep the stitches on the left needle, then knit them again tbl, but this time slide them off onto the right. This is a cluster2tog and every time after that it calls for a cluster2tog, this is what you do. It's basically a k-fb, but with two stitches at a time.
Is this the same as what is written in your pattern?