How about just purchase a USB BT adapter for $10?
That laptop was built for Windows XP.
Dell is one of the manufacturers that doesn't fully support newer OS environments, and they don't have to if the hardware wasn't built with that OS in mind, not to mention their customer support team will tell you to downgrade the OS.
If the hardware works, great.
If not, don't expect too many miracles.
Sometimes 3rd party drivers work, but it being a Dell product, it has special firmware in it that is developed and managed by Dell, and they get to choose whether there is true native support from other operating systems higher than what the hardware was intended. By choose, meaning "continued support through ongoing development & future compatibility."
Older systems also have hardware that may likely be faulty as well, with the interconnect components, motherboard sockets, for example where no matter how often a modular attachment is replaced, the main board won't properly register modular interconnects properly.
And then of course, make sure 'discovery mode' is turned on and that the physical/software wifi/bluetooth "enabled" switch is deactivated and then activated to allow registering of the component.
There's probably likelihood that the device works better under Windows 8.1 than it does on Windows 10, not to mention a 32-bit version instead of a 64-bit.