Flexpool has some excellent steps on how to get started and also on installing MadMAx

https://www.flexpool.io/get-started/xch/XCH-CLI?primaryServer=xch-us-west.flexpool.io

The one caveat is that on Ubuntu 20.04 you’ll need to install cmake

sudo apt install cmake

Then you can install and run MadMAx with

git clone https://github.com/madMAx43v3r/chia-plotter 
cd chia-plotter 
git submodule update --init 
bash make_release.sh 
sudo mv build/chia_plot /usr/bin

Now you can create a plot by running the chia_plot command.

chia_plot -n 1 -t /path/to/tmp/ -d /chia/destination -c p2singletonaddressorpoolcontractaddress -f biglongfarmerpublickey

Note that if you are plotting on a harvester that the p2 singleton or the pool contract address does not have to be on the harvester system. You can grab it off the main node and then use the address on the machine plotting.