Unauthorized error when following "Desktop app calls Web API" instructions

> Please provide us with the following information:
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### This issue is for a: (mark with an `x`)
```
- [ ] bug report -> please search issues before submitting
- [ ] feature request
- [x] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)
```

### Minimal steps to reproduce
> Follow the instructions completely. Then change the tenant to `common` in both App.config and appsettings.json. Then, sign in with personal microsoft account


### Any log messages given by the failure
> "An error occurred while getting /api/todolist > Unauthorized"

### Expected/desired behavior
> No errors.

### OS and Version?
> Windows 10 19042

### Versions
>

### Mention any other details that might be useful

I understand that the instructions say "this sample does not work with personal microsoft accounts". What do I have to do in order to protect an API using personal microsoft accounts? This sample is everything that I need, except that I just need to accept personal MSAs from users. Please help!

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