Theoretical load spread through concrete is roughly 2:1 (vertical:horizontal). For a 1.5m thick footing, load spreads 3m laterally. Ensure your footing dimensions exceed the mast base plate plus 3m on each side.
Easily export the sheet to PDF for submission to local building authorities. If you'd like to build this out further, let me know: What crane model are you designing for? Tower Crane Foundation Design Xls