The use of Liquorice is to my mind likely to end you up with an inappropriate taste.
It all depends on exactly what is meant by Liquorice, do "they" mean liquorice extract, soft liquorice, hard liquorice - God knows there are all sorts of options & if you attempt to use even a small potion of a hard liquorice stick you will end up with a liquorice drink with a stout flavour.
I know because when I first started brewing (50 years ago) using English recipes ( they turned out to be worthless), liquorice was a common theme with the darker beers. I soon learned to give liquorice a wide berth.
Of course there may well be a well defined way to obtain a controlled flavour addition using Liquorice, but until you can pin down that procedure please be very wary. The fact that that you have a recipe which does not precisely specify the type of liquorice would set warning bells off for me.