Stoq's homepage is located at:
https://www.stoq.com.br/
You can fetch the latest source code from github:
$ git clone https://github.com/stoq/stoq.git
To install stoq you have to install Poetry and run:
$ poetry install
Then check everything has been installed correctly run the tests:
$ make test
And see if stoqdbadmin has been provided:
$ stoqdbadmin help
There is two mailing lists for Stoq. You can subscribe to them through the web interface at:
http://www.async.com.br/mailman/listinfo/stoq-users http://www.async.com.br/mailman/listinfo/stoq-devel
Stoq itself is covered by the GNU General Public License (version 2.0, or if you choose, a later version). Basically just don't say you wrote bits you didn't.
However, some parts of it are covered under different licesenses, see:
docs/copyright for more information