I am a luddite on these issues. I have LR 5.7 installed on my iMac. I bought a standalone, full version, not upgrade as this is not available, DVD of LR 6. Will the LR6 installation process overwrite / upgrade LR5 to LR 6 or will I end up with two versions of LR on my computer? If both versions are installed, how do I migrate the current LR 5 catalog with all the adjustments to LR6? I am not at all interested in, nor want to subscribe to CC, btw. How do I avoid subscribing to it during installation?
LR 5 and LR 6 are completely separate programs that can both be on your computer at the same time. After you install LR 6 and start it, you will be prompted to upgrade your catalog. You should allow this to be done. This creates a new copy of your catalog, and retains all of your work that you have done previously. But it is in the format that Lightroom 6 needs. The original Lightroom 5 catalog remains on your computer, intact, and usable by Lightroom 5. It is then up to you to decide when/if you should uninstall Lightroom 5.
Thank you. I assume, I will not be instructed to subscribe to CC during the installation process?
Sorry, but I cannot advise you on that. I am subscribed to the creative cloud. Just follow the instructions. If you run into problems come back to the forum. There are a number of remedies if you encounter problems.