In order to use the functions of LocFreeClassGrp.m one has to type Attach("RelAlgKTheory.m"); If G is a finite group of MAGMA type GrpPerm, then C := LocallyFreeClassgroup(G, true); or C := LocallyFreeClassgroup(G, false); both compute the locally free class group C`cl and the kernel group C`D. The second possibility should in principle be faster. Simply try load "SmallGroups.m"; (This takes a long time; you should maybe use a shorter list orders.) or load "Metacyclic.m";