Selected user account does not exist in tenant 'UserVoice, Inc.'

I'm trying to login and vote on https://feedback.azure.com/forums/915433-azure-sphere/suggestions/36196912-allow-for-transfering-device-ownership

While using my personal microsoft account, it says "Selected user account does not exist in tenant 'UserVoice, Inc.' and cannot access the application '91a42e81-999b-4cf1-aa36-bb33f25ff53b' in that tenant. The account needs to be added as an external user in the tenant first. "

As I understand, it's a problem on UserVoice tenant and i have no access to it to add my email as guest user.

You need to login with a Azure Active Directory user account, personal account is not allowed here.

The login endpoint is https://login.microsoftonline.com/common/oauth2/authorize?client_id=91a42e81-999b-4cf1-aa36-bb33f25ff53b&redirect_uri=https%3A%2F%2Ffeedback.azure.com%2Fauth%2Foidc%2Fcallback&response_type=code&scope=openid+email+profile+offline_access&state=98a2f664a4ff12e695a7d482dbf1f6a07a0901f95171d70f6cb779639b71e979&sso_reload=true

It is a multi-tenant application with v1.0 endpoint. So you can login with any Azure Active Directory tenant users. Only v2.0 endpoint supports personal accounts.