Excel Crossword / Cryptogram Maker

My second project in Excel was to create a cryptogram (or crossword) template.
The goal was that in one tab the cryptogram creation tool can fill in the answers in a diagram of 21 by 21 boxes. 
Excel then determines the numbering of the answers and colors the empty boxes black. 
The cryptogram maker can then add the questions to the numbers.
As soon as the cryptogram maker is ready, the puzzle is transferred to a 2nd tab where the “customer” can start making the puzzle. 
Naturally, the cryptographer will have to hide the answers tab (possibly with a password).