Yosemite to El Capitan

MBP 13" Early 2015. Currently on Yosemite (10.10.5).

Mostly for Metal, I am interested in now upgrading to El Capitan (10.11.x). I have no interest in moving to macOS Sierra at this time. Apparently Apple is not really a fan of what I'm trying to do and has made it very difficult for me to just upgrade to El Capitan.

I do not have it listed in my "Purchased" tab of the app store. Further, the direct link to download El Capitan from Apple gives me a fun modal:

This version of OS X 10.11 cannot be installed on this computer.

Presumably this is because it is for Snow Leopard upgrades.

Anyway, any help on how to install El Capitan is appreciated. Googling has not been helpful.

After more research and other similar questions on Stack Exchange, I have come to the solution I was originally looking for.

This website provides some instructions, but more importantly direct links to the .pkg files for El Capitan on the osxapps.itunes.apple.com domain. You can then use the checksums from this git repo to verify the installers if you still feel something is fishy.

I also spent about an hour on webchat with Apple support trying to get El Cap added to my purchase history for my Apple ID, so I could just download it from the App Store, to no avail. Their official recommendation was to find it on a third party site. Couldn't believe it. They also noted that going into an Apple Store / Genius Bar may yield results with getting it installed (or any Apple Authorized store), at which point backup media could be created if it ever needed to be reinstalled.