In kind interest payments let the lender increase the principal balance instead of actually paying interest. In this case it would be like issuing 10% more equity per year instead of paying the 10% in cash. It wasn't mentioned in the article if they have that option, but it wouldn't surprise me.
Fwiw I'm parsing this as the interest to service the debt topping out at 10% rather than 15% (which imo is a pretty big difference)