I installed DS4Windows 1.5.15 on m'laptop, also Windows 10 x64 build 17134.
Exclusive mode does not work.
Installed HidGuardian, and added the appropriate hardwareIDs to AffectedDevices in the registry. Just like on my desktop, the Bluetooth interface is able to connect to my wireless controller, but nothing appears under USB Game Controllers.
I know that if it never shows up there before I've launched DS4Windows, then there's certainly nothing for it to hook onto, let alone for it to run in exclusive mode. Either way, looks like Exclusive Mode is straight up broke again -with or without HidGuardian.