Hi @Tomislav Crnilo (SMART GROUP SERVICES d.o.o.) ,
Welcome to Microsoft Q&A forum and thanks for reaching out here.
Are you trying read Excel files from Sharepoint Online using ADF? If that is the case you can refer to this article which has a demonstration on how to achieve it using ADF: How to read files on SharePoint Online using Azure Data Factory
Here is related MS Doc: Copy file from SharePoint Online using ADF
Hope this helps. Please do let us know how it goes.
Thank you