Run the following commands:
cd /usr/local/directadmin
wget -O custombuild.tar.gz http://files.directadmin.com/services/custombuild/2.0/custombuild.tar.gz
tar xvzf custombuild.tar.gz
cd custombuild
./build all d
Then, go to DirectAdmin dashboard > Plugin Manager > Add
Type the URL: http://www.custombuild.eu/plugin/custombuild.tar.gz
And type the DirectAdmin password at the password field, then click on "Add", You're done.!