If you have never installed a version before v54 then you do not need to do anything.
[jcbContentMania.MutJCBSetupMania] sPlayerManiaWeapon=jcbContentMania.WpnJCBSetupMania sCurrentMapClassName=DM-DesertIsle sCurrentFileName=Second AddedObjects=(smap="DM-Antalus",sFile="New List",sType="Vehicle",sName="Manta",sClass="Onslaught.ONSHoverBike",vLoc=(X=-2132.850098,Y=-1119.040039,Z=-55.939999),rRot=(Pitch=0,Yaw=2861,Roll=0)) AddedObjects=(smap="DM-Antalus",sFile="New List",sType="Vehicle",sName="Scorpion",sClass="Onslaught.ONSRV",vLoc=(X=-2397.439941,Y=-2154.489990,Z=-439.399994),rRot=(Pitch=0,Yaw=3827,Roll=0)) ... [jcbContentMania.MutJCBPlayMania] sPlayMapClassName=DM-DesertIsle sPlayFileName=Second sSetPower=powered UseFile=(smap="DM-Antalus",sFile="New List") UseFile=(smap="DM-DesertIsle",sFile="Second")CHANGE TO:
[jcbContentMania.MutJCBPlayMania] sPlayMapClassName=DM-DesertIsle sPlayFileName=Second sSetPower=powered UseFile=(smap="DM-Antalus",sFile="New List") UseFile=(smap="DM-DesertIsle",sFile="Second") AddedObjects=(smap="DM-Antalus",sFile="New List",sType="Vehicle",sName="Manta",sClass="Onslaught.ONSHoverBike",vLoc=(X=-2132.850098,Y=-1119.040039,Z=-55.939999),rRot=(Pitch=0,Yaw=2861,Roll=0)) AddedObjects=(smap="DM-Antalus",sFile="New List",sType="Vehicle",sName="Scorpion",sClass="Onslaught.ONSRV",vLoc=(X=-2397.439941,Y=-2154.489990,Z=-439.399994),rRot=(Pitch=0,Yaw=3827,Roll=0)) ...The entire [jcbContentMania.MutJCBSetupMania] section can be deleted, or left, as it is no longer used. It is replaced by a section called [jcbContentSetup.MutJCBSetupMania] so could be renamed.