However, note that Daz has announced that new "Starter Essentials" will focus on Genesis 9. If you plan to buy future products, you will eventually need to upgrade.
Because Genesis 8.1 (G8.1) is an evolution of Genesis 8 (G8), the installation process is slightly different from previous generations. It is not a single "standalone" file; it is a platform update within the Daz Studio ecosystem.
Use your favorite Genesis 8 hair and clothing seamlessly.