To use it, right-click on it and run as administrator.
To make it launch at startup, create a task in Task Scheduler (check "run with highest privileges" when creating it).
If you want the latest Store version: go here, paste the store link of the app, click the checkmark and then scroll down and download the one named "SAMSUNGELECTRONICSCoLtd.SamsungQuickShare_xxxxxxxx_neutral_xxxxxxxxxxxxxxx.msixbundle". Then open it and install it. You won't need to download every update like this, it'll automatically update from the Microsoft Store when there is a new version. Keep in mind that latest versions from the Store can contain patches to this method, so if you encounter any issue download this version here that has been reported to be more stable. If you encounter issues also with the older version I linked, they've probably patched it Android-side (and I can't do anything about it, especially without root).
Remember that your phone's screen needs to be on and unlocked to be able to find it from your PC (unfortunately it's a limitation of Quick Share itself)!
If your PC doesn't have an Intel AX wireless/wifi/bluetooth card (e.g. Intel AC/Broadcom/Realtek/Marvell etc.) you'll also need to apply "DriverCheckBypass.reg" (otherwise it won't find your phone and viceversa)! To do it, just run the file, then Yes and then Ok.