Really not sure why you are having so much trouble with this tbh, you cant download and directly install Windows 10 on the XP computer but you should be able to use the download for use on another computer option, is this the option that you have been selecting.
Tip
If using a computer and not a mobile phone, please avoid adding multiple posts while waiting for us to reply to your last, edit your last post to include anything that you wish to add, this will ensure nothing gets overlooked which can sometimes happen if a thread has more than one page.