Power BI user who is publishing the report should have a Power BI Pro license.
Users viewing the embedded report need either a Power BI Pro license or the content needs to be in a workspace that’s in a Power BI Premium capacity (EM or P SKU).
The user needs to sign in to view the report whenever they open a new browser window.
Some bowsers will require that the users refresh the page after sign-in, specially in scenarios where InPrivate or Incognito modes are used.