Manually copy iTunes music from MacBook to iPhone

Please read again -> Related Article -> Manually manage content on your iPhone, iPad, or iPod touch using your Mac

Interesting; that article specifically says Mac OS Catalina; I don’t know if it works for later versions like Big Sur (Mac OS 11) or Monterey (Mac OS 12). And the article has been archived; I couldn’t find an updated version. I would like to know if it works. I’m not going to try it, because if you enable manually Manage it deletes all the content already on your iOS device and you have to start over.

And OP has OS X 10.11 -> macOS El Capitan.

See also in that Apple article-> In macOS Mojave or earlier, you can manually manage your content using iTunes. Follow these steps.

You're welcome.

Yes, I see that.

In macOS Monterey it works via the Sidebar -> click the iPhone.

Then is possible toe select manually the stuff to add to the iPhone.

It works the same.

Great, thanks!

I misread the OP’s version as Mac OS 11, rather than 10.11. So it was all downhill from there 😏