Lost Cities + Biomes O' Plenty world gen not working

So I'm using the server provider "Exaroton". I'm trying to set up the world gen so it goes as the following: Lost Cities + Biomes O' Plenty using Rare cities. I put this into the Generator settings as: lostcities_bop:rarecities and it didn't work. I tried the same thing in the world type, and it didn't work either. What am I doing wrong? Thanks in advance!