Thanks for using Bitnami. If you followed the instructions the lego client should be installed in
/usr/local/bin. Please check this is the case by running:
ls -l /usr/local/bin/lego
If it is there, please check that
/usr/local/bin/ is in the path. If not just run
sudo lego --email="EMAIL-ADDRESS" --domains="DOMAIN" --path="/etc/lego" renew
If the executable file is not there, please follow the instructions above to install it.