to be specific, does the variable have to be named ‘open link’, or just have to contain ‘open link’ to be in the name? How would I go about having multiple ‘open link’ variables in a project?

I'll move this over to the Advanced Topics section for you - that's a better fit for this kind of topic

Based on the documentation, it looks like a cloud variable has to be named exactly like the examples.

Why do you need multiple open link variables in a project?
Why can't you just set it multiple times?