Github Desktop Authentication Failed

Actually, the guy above, @bhoeschen, is spot on.

Instead entering your VSTS / Azure DevOPS username and password, rather create a Personal Access Token (PAT), and use that for the password.

https://docs.microsoft.com/en-au/azure/devops/organizations/accounts/use-personal-access-tokens-to-authenticate

Condensed instructions from that page:

1. Sign in to either your Azure DevOps organization
2. From your home page, open your profile. Go to your security details.
3. Create a personal access token.
4. Name your token. Select a lifespan for your token.
5. Select the scopes that this token will authorize for your specific tasks.
6. When you're done, make sure to copy the token. You'll use this token as your password.