To export records (such as your clients) as a CSV file (with tab as a separator, so “TSV” would technically be more accurate, but it is less common) or as an Excel file, first select a dataset in the sidebar catalog, then click the three dots in the upper part of the workspace area and select the appropriate menu item.
Please note: only those records that are currently displayed or being used by the current representation, taking into account access settings and applied filtering parameters, will be included in the exported file.