A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.
Dear FBHeyde,
You may use Microsoft Flow as follows to do that. You can use the Copy files between OneDrive for Business and SharePoint flow template and then edit the template as follows. When adding a new file in a folder in a site library in a shared site in SharePoint Online, the newly added file will be copied to a folder in the OneDrive for Business site.
If you have more advanced requirements, you may need to edit the code in the flow. We have a dedicated forum Microsoft Flow Community for the Microsoft Flow related issues and questions, I suggest you post a new thread there for further help if you have some advanced requirements.
Best Regards,
Cliff