RE: Dell Inspiron 15R 7520 SE - Windows 10 64 Bit WiFi Driver not available on Dell Site
On the Drivers & Download pages for the Inspiron 15R 7520 there are only 64-bit options for Windows, whether 8.0,8.1, or 10. So those drivers are the ones for the 64-bit version of Windows 10, as long as you filter the operating system option to Windows 10 64-bit.
The file name may state "Win32" but if you click on the "View Details" link, and then check "Supported Operating Systems" near the bottom of the page you'll find that the driver supports both 32-bit and 64-bit versions.
You don't mention which wireless card you have in that system so I can't link directly to the specific driver. Which card do you have and what error are you getting when trying to install the drvier?
I would also recommend updating the firmware on your router. Many routers need an update to be able to handle Windows 10 specific drivers and cards reliably. What router brand and model are you connecting to? And do you have problems with all routers or just this one.
Lastly, here is a link to the Dell Networking & Wireless Support Center. You will find a few support articles in there that may be of help to you.
Let me know which card you have and when the last time you updated your router and, if you can't get the connection to work, I'll see what else I can suggest to help you.