I am stuck getting power bi embedded working. I keep reading that I need to register an application in Azure/Power BI.
I have an existing web application. Does that mean I can skip this step of creating one? https://app.powerbi.com/embedsetup/AppOwnsData
note: I'm trying to set this up with AppOwnsData, masteruser.
Is this where I add appropriate permisions if adding to an existing one?
and if I am adding permissions to this existing azure app, then does my user need permission to sign in to this particular app or just power bi?
To generate an embedding token for Power BI your application code must first get an access token for Power BI, and to do this you must use the ApplicationId of an application registered in Azure Active Directory.
You can use an existing AAD Application, but the online wizard creates a new one for you with the appropriate permissions to create a new (additional) AAD App just for Power BI Authentication.
The required permissions are documented here, although you should at least test with the wizard-created application first.