Hi droopy,
As mentioned into the README, you have two steps. Open a terminal and,
first, create a "device" (Public/Private key pairs) with the following command :
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$PWD
./activate -u <AdobeID USERNAME>
Then (a
.adept directory is created), you can download your ePub with :
./acsmdownloader -f <ACSM_FILE>