Power BI server Sharepoint Credentials don't recognize

Hello guys,

I need your help, I made a Power BI report using data from a Sharepoint Folder (the report combine all the Excel files in the Folder). I set the credentials of my Organization and it works perfectly in Power BI desktop. 

The problem comes when I published the report in the server. I tried to set the scheduled refresh, unfortunately it shows me this message:

The Web Data Sources are Sharepoint connections too.

I have been looking for help in the forums and in the page of support from Windows (https://docs.microsoft.com/en-us/power-bi/service-admin-troubleshooting-power-bi-personal-gateway). 

Since the Sharepoint is in cloud I do not need to set a Gateway connection. When I tried to updated the credentials this message appears me:

Error message after trying update Windows Credentials.

Do you have any idea why the server is not recognizing my credentials and why when I tried to updated them an error occurs?