Hi Cinebeast, CSV is the right format to use. You can import it like any other file (drag&drop, with the import button, or by placing it anywhere in the content folder if monitor content option is on). When you try to import it you should get a prompt for which kind of data asset to create, select Dialogue_TableItem (note, UE4 sometimes doesn’t show this data row type, if this happens try opening DT_Dialogue_Main and trying again to make the editor aware of that type)
In the sample project, I placed the CSV files in the “SampleContent/DialogueSampleContent/Data” folder, in my case UE4 automatically detects a change and updates the datatable or prompts to create a new one from the CSV file - I believe this is the ‘monitor content folder’ option in editor settings, I’m not sure if this is on by default.
For more info on data tables, have a look here