Popup input window when cell is selected

I am after some help on how to get a popup input window to appear whenever any single cell in column C is selected, and then whatever data the user inputs is returned only to the selected cell.

Any help would be appreciated

Why ...?

What if someone is repeatedly clicking the left arrow to get to Col A and they don't want to enter anything in Col C?

I was too wondering why.. not sure.. but heres one way to do it i guess.. using a helper cell in Z1.

WorkSheet Code

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Save Button code on Userform (with textbox1 and Commandbutton1)

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