Lightroom version 5 is different than Lightroom version 6. You can have both installed on your system and they operate independently.
Catalogs from LR 6 are not compatible with LR version 5 and vice versa.
The latest version of Lr 5 is Lr 5.7.1 which uses the processing engine equivalent to Adobe Camera Raw 8.7.1
The Latest version of LR CC 2015/LR 6 is 2015.12/ LR6.12 which uses the processing engine equivalent to Adobe Camera Raw 9.12
They will function differently. Period. ( Important to note Adobe Camera Raw is a plugin which functions in Photoshop, Lightroom does not use the Camera Raw Plugin the processing engine is built into the specific LR Application you are using)
If you wish to upgrade your LR 5 stand alone version to LR 6 then that is a paid upgrade you cannot update.
I've tried to update to version 6.7. However, when I hit the download button for this version, it automatically updates my "CC" version,
If you have LR CC, it will update LR CC. If you have LR 6, it will update LR 6, regardless of any wording that may appear that would indicate it is updating LR CC. The same download and updater is used for both LR CC and LR 6, and you will receive the one you paid for (LR CC or LR 6) and not the other one.
I've tried to download Lightroom 6 (without purchasing, in attempts to do a trail run) but when I am prompted to sign into my Adobe ID to download, it says that my current account grants me full access to Lightroom and it automatically downloads as CC.
Do I need to make a new account all together in order to download 6?
Thanks for your help.
There is no trial for the LR 6 standalone version, just a trial of the CC version. The application is the same, if you end up purchasing the stand alone license then you will use the license key to switch.
However if you already have the CC version installed on the computer I do not think it will allow another trial.