Hello,
You can use the datagrid extension widget to add an inline button to your datagrid that triggers a microflow.
For upload:
The microflow will have one parameter the same type as the datagrid, then you can open a popup page then pass the object and use the file manager widget to upload the file.
For download:
In the microflow use the download activity to download your file. The microflow will have one parameter the same type as the data grid.
Hope it helps!