I want to embed a report where the user logins in the website with his personnal account (that will be sold through a monthly plan), he logins in and uploads his .csv or other Excel formats, and the report reads his data source.
I'm sorry I don't quite understand your needs. Do you want to embed a report to the website, but the report reads the data(csv,excel files) uploaded by the user? Or do you want to embed a report into your organization's application and then your users can view this report as described in the official documentation you mentioned? If the latter is the case, are you having trouble with Step 2 - Create a Power BI workspace? If so, do you have a Power BI account with a PRO license or PPU? If so, you can log in to Power BI Service and refer to this document to complete this step. Otherwise, please check out this video below. Hope it can help you.