I'm having trouble interpretting how to submit the solution to the Logic 3 challenge - I have "filled the boxes" with letters that fit the rule, but it's not to clear how to write it down as a single string for the solution. Especially the "with spaces where necessary" part raises confusion.

If the boxes are filled as follows:

  1
2 3 4
5 6 7
8 9 x
  y

What should be written down as solution?
"123456789xy" ?
" 1 23456789x y " ?
Something else?

Did you try it vertically?