Downloading Installer
iDempiere version 11 is maintained and stable. This is the recommended version to install for implementation and production purposes.
You can find daily installers for this version at https://sourceforge.net/projects/idempiere/files/v11/daily-server/
For example, you can download the latest with these commands:
wget https://sourceforge.net/projects/idempiere/files/v11/daily-server/idempiereServer11Daily.gtk.linux.x86_64.zip
wget https://sourceforge.net/projects/idempiere/files/v11/daily-server/idempiereServer11Daily.gtk.linux.x86_64.zip.MD5
md5sum -c idempiereServer11Daily.gtk.linux.x86_64.zip.MD5
The next step is Installing from Installers
Daily Installers for Development version
Daily builds for linux64 and windows64 platforms can be found here: https://sourceforge.net/projects/idempiere/files/devel/daily-server/
Development version is pretty stable, but it can be at some times unstable, so it is recommended to install it for testing purposes, and to check new features, but not for production.
Previous Release Installers
You can find the official installers for previous releases (with corresponding MD5 checksum) at sourceforge: https://sourceforge.net/projects/idempiere/files/
Please note that iDempiere becomes rolling update maintenance. Installing a previous version is not recommended.