I’m installing a clear separate ConTeXt. I’ve installed it in /Applications/context/. According to https://wiki.contextgarden.net/Mac_Installation:

Creating an Engine for TeXShop

Actually, engine is somewhat misleading. In TeXShop an engine is a script that contains commands that are use to typeset your documents. TeXShop comes with many engines set up to run TeX, LaTeX, Xe(La)TeX and ConTeXt MKII and MKIV that have been installed via MacTeX.

If you want to use ConTeXt Suite you will have to create an TeXShop-engine.

If you have not run TeXShop start it so that the support files for TeXShop are installed for you.

Since in the newer versions of MacOS the users Library-folder is hidden and not accessible from within TeXShop we will use the terminal for simplicity reasons. If you wish you can access the your Library-folder from the Finder and navigate to the Engines-folder inside of the TeXShop-folder inside your Library-folder and choose a ConTeXt-engine.

Start the Terminal you will find it in the Utility-folder in the Applications-folder

Find your username is, if you do not know it already.
The command whoami will output your user name.

Open the standard MKIV engine for TeXShop enter

open -a TeXShop $HOME/Library/TeXShop/Engines/ConTeXt\ \(LuaTeX\).engine

This will open the file in TeXShop and switch to TeXShop

But this .engine file does not exist. There are no .engine files at all (just an Inactive directory). So, what should I do?