To add players as admin create a file in the Cluster_1 directory called adminlist.txt
Find the players ID in the directory
YOURSAVEDATA\DoNotStarveTogether\CLANHOST\Master\save\session\XXXXXXXXXXXXX
In this directory you will see a bunch of folders named like the following..
KU_EXJXHQYQ_
KU_G2eyNZuC_
Insert this into your adminlist.txt file without the trailing underscore for the player you want as admin.
More info here on how to get the players ID
http://forums.kleientertainment.com/topic/47206-admin/