I had to choose a smartphone when my old dumb phone died (couldn't get batteries for it anymore), and figured bugger it, I despise Android, despise Apple (it's over-priced rubbish), and use primarily, Windows, so went with the Lumia 550.
Whilst a pain, it's been better than the alternatives - until now.
Why exactly, do you make it so god damn difficult to connect the phone to the laptop, so the SD card can be accessed? (have you guessed I've not went with Windows 10 for my laptop yet? (get rid of the Fisher Price UI, telemetry, forced updates etc and I may try it again).
I went to the site (https://www.microsoft.com/en-gb/mobile/support/product/lumia550/) to find the software, and I'll be damned if I can find it. Not surprisingly, Windows 7 (yep, I hate 8/8.1 too) can't install the driver either - ah the joys.
If you're going to do this - do it right! (hint: the OS SHOULD NOT MATTER!)
Oh and no, once I found the "Windows Phone app [sic] for desktop", it did NOT help (couldn't find the phone .......... what a surprise (and yep, the "Find my phone" option is beyond useless)).
Can't exactly recommend others get a Windows phone if it doesn't even do basic things like USB sharing without an extremely bad headache (I've fixed Android etc phones and in most cases, I can either use the SDK, or the SD card shows up when I plug the phone in)