They secured US$10m in funding back in 2015 under their former name, PayItSimple, a year or so after they released their platform to the US market. Also believe there were other seed rounds thereafter.
Cash proceeds from this IPO aren't 'directly' being used to reduce debt, instead they issued more shares via the execution of convertible loan to address most of that.
Memory is a bit hazy, sold long ago, but that's the gist of it.