fail to connect sharepoint Data source in power bi report server

As documented here Power BI report data sources in Power BI Report Server - Power BI | Microsoft Learn Sharepoint Online is not supported for scheduled refresh. Report Server is designed for scenarios where you cannot use any cloud resources for storing data. If you have a hyrbid scenario where some data is on-prem and some is in the cloud then you can either publish your report to the Power BI cloud service and use a gateway to connect to the on-prem data or you will need to pull your Sharepoint data down to an on-prem source which Report Server can do a scheduled refresh against (like a SQL database)