If you're looking for older versions of Cosmo, you can download them here:
Most of our products install through 'suite' installers. When using a suite installer, you do not need to install everything in the suite; you can select just the plugins you want to install and proceed from there.
Those and other installers for older products are found on our Legacy installers page: redgiant.com/legacy
For older builds of the current version of Cosmo, visit its Downloads page.