The missing “lpadmin” group can be replaced by the always present “adm” group of the system. I simply build with
./configure --with-system-groups='sys adm root'
make
and then users in the “adm” group can do administrative tasks as creating a queue with the lpadmin command or logging into the admin part of the CUPS web interface. At least in a classic system the first created user is in the “adm” group.