@MrT10001 It was issue that windows picked wrong driver even I installed oneplus original driver. I got it work in windows test mode. I'm not sure why it not changed, maybe reason was my internet connection because it was not worked good.

@MrT10001 This issue was mentioned in XDA, n100 model.

My device isn't detected

Go to device manager and make sure your phone shows up as QDLOADER 9008.
If it shows up as QHUSB_BULK, it means Qualcomm driver wasn't installed automatically by Windows Update. Download the latest one from Microsoft website at... their links not work anymore.

@frifo

I installed ubuntu touch before to Oneplus n100. In this phone windows not anymore offered drivers. I downloaded oneplus drivers for windows from oneplus website and I needed to change windows to test mode to use drivers. I used windows 10. After I changed test mode back to normal mode.

@HarryBass

I was have similar situation with my Oneplus nord N100.
When I connected new flashed OxygenOS to wifi network then I was able to change OEM-unlocking option setting and after that unlock.