tangerine,  You'll need to use a computer to download Windows 7. Even a computer running Windows 10 has Internet Explorer.   You should be able to download Dell Recovery Image Download   Rick
How do I access and download software from My Dell Downloads after I install a new hard drive? Specifically Windows 7. I tried to access it from different devices I have but it appears that it needs to be from the original computer because it wants to check my service tag. I can't use my original computer because the current hard drive is bad and the new one won't have Windows installed until I'm able to download it from Dell. 
My Dell Downloads