This is from their support, what they say about logging into Netflix.
Please try the methods below to see the reslt.
1.Please delete the two folders and then run StreamFab to try again and see the result.
%HOMEPATH%/Documents/DVDFab/StreamFab/Temp
%HOMEPATH%/Documents/DVDFab/StreamFab/log
2.Do not use a VPN, or try using an IP address from the country corresponding to your Netflix account.
3.Please reset the password in the browser and then tick the option "Sign out all devices" and only leave StreamFab to try again.
4. In the Edge or Chrome browser, confirm whether you can log in normally.
5. Restart StreamFab, log in to Netflix again to see the result.
6. Clear website cookie in browser to see if you can still log in
7. Please try the previous version 6170 to see the result.