downloading windows 10 iso file on mac

i have a mac air and ive downloaded the 64 bit windows 10 iso file from the Microsoft website and opened the file on bootcamp. i did everything that the microsoft website said to do but when i press install on the bootcamp page, it says it needs a 64 bit windows 10 iso file. i have no idea what to do. i did everything correctly and it took so long and i thought i was finally done but then this came up. what do i do now?