Dataset refresh from OneDrive Excel file set-up

Thanks Gilbert and Maggie,

The issue is resolved now. For some reason, OAuth2 was not populated as an option for 'Authentication Method' in DataSource Credentials when I had posted my issue. So to resolve, I redid the steps as follows:

1. I signed into my desktop and reentered the data source for all the excel files(onedrive) and made sure the permission for each file was set to 'Organizational Account' with Privacy level 'Organizational'. I also made sure that I was signed in as authorized user for each file.

https://docs.microsoft.com/en-us/power-bi/desktop-use-onedrive-business-links

2. I saved and upload this .pbix file to OneDrive for Business and imported in PBI Service using get data.

https://docs.microsoft.com/en-us/power-bi/service-connect-to-files-in-app-workspace-onedrive-for-business

3. This time, 'Edit Credentials' was enabled (earlier it was disabled) and I signed in for each and every excel file. And this time I was able to choose 'OAuth2' as Authentication method. No need to install/configure gateway. I Used OneDrive Refresh and I scheduled refreshes and looking at the refresh history, it worked great. 

https://5minutebi.com/2018/04/09/power-bi-using-and-refreshing-excel-datasources-with-onedrive/

https://medium.com/@Konstantinos_Ioannou/onedrive-powerbi-desktop-use-valid-paths-to-import-data-stored-in-onedrive-for-business-60089848e594

I have provided the links that were helpful. However, with the continuous updates from the microsoft team, some of the screenshots provided won't look exactly the same.