How to use calendar date picker xlsm files exactly?

Hello

Recently I asked about calendar date picker feature in Excel. I found several xlsm files developed by community members but I'm still not sure how to use them exactly.

Can someone help?

Can I have it so that these programs apply to an entire column in my entire workbook? So that when I click any cell in that column in any sheet in that workbook, the calendar appears and I pick a date and CHOOSE which format it is input in text in said cell?

Example I found online