Don't understand coding for Weekly Note dates

Things I have tried

I found a weekly note template that goes like this:

S {{sunday:DD}} · M {{monday:DD}} · T {{tuesday:DD}} · W {{wednesday:DD}} · T {{thursday:DD}} · F {{friday:DD}} · S {{saturday:DD}} »

What I’m trying to do

I want to click the links and have it create the day note, which is what I think it should do (according to the template author). But when I click it, I get the error that filename can’t contain a colon :

So how is this supposed to work? I think I am just being completely stupid about it.

And I find this format everywhere. From another template:

SUN

![[{{sunday:gggg-MM-DD}}#Notes]]

But if I click that link to create the file, I get the same error. What am I missing about this?