I have installed Adobe Lightroom CC 2015
So back in 2015, Adobe published Lightroom v6 (perpetual) and Lightroom CC 2015. Both were actually a flavor of v6, but the latter was the first subscription version. It had a few (very few) extras over the perpetual v6, but mostly was the start of requiring a subscription. This was the end of the perpetual model (perpetual a.k.a. stand alone) and the last supported version was v6.14. Lightroom CC 2015 was eventually renamed, Adobe dropped the CC part, and currently is called/marketed as Lightroom Classic, currently at v12.5 (v12.5 will not work on your MACOS El Capitan)
Now you installed Lightroom CC 2015 in July of last year, used it for awhile (how long? less than 7 days?) and, now, after a long period of time, it is requesting that you subscribe. Sounds like a trial period ran out.
Other members, Do I have that correct?
You will probably need to uninstall Lightroom CC 2015, a complete uninstall (link 1) . If you installed (long time since CC 2015, so I forget) the Adobe Creative Cloud Desktop App, then that will also have to be completely uninstalled (link 2) as it will foul up licensing of v6.14. Then you will need an link to a download of v6.14, followed up by installing 6.14. (perhaps in link 3)
Some links:
- How and when to use the Creative Cloud Cleaner tool | Advanced steps
- Uninstall the Creative Cloud desktop app
- End of Support | Lightroom 6 Downloads and Syncing (I think this may include v6.14 download links)
ah, another link for v6.14:
https://prodesigntools.com/adobe-lightroom-6-cc-direct-download-links.html