Make the rpcuser and rpcpassword whatever you want, but they must be the same for DriveNet and the sidechain(s).
DriveNet (~/.drivenet/drivenet.conf):
rpcuser=drivenet
rpcpassword=drivechain
server=1
Sidechain One (~/.sidechain/sidechain.conf):
rpcuser=drivenet
rpcpassword=drivechain
Payment sidechain (~/.payment/payment.conf):
rpcuser=drivenet
rpcpassword=drivechain
./sidechain-qt
./payment-qt
If you are going to use the automated BMM page, you must start DriveNet with the --minersleep option set. Set this value higher than the automated bmm refresh interval. For example, if the refresh interval is set to 1 second, set --minersleep=1500 (1.5 seconds).
./drivenet-qt --minersleep=1500
Turn on automated BMM, and set the refresh interval to anything faster than what --minersleep has been set to.