Hi,
seems someone forgot to properly setup the groups. As there are two empty groups, Mageia Bug Hunters and Mageia Helpers all the people that apply there can never successfully join without an admin intervention, as the groups management are normally done via the group leaders. Empty groups have no leaders, so noone to manage themselves.
This issue has already been partly mentioned in viewtopic.php?f=18&t=1951 but sadly no reaction/change so far.