Start with a repeating list
Open a regular web page with the data you need. Find lists can suggest repeating elements; manual selection is available when a suggestion does not match the list you want. Browser-internal pages cannot be scraped.
Check before collecting
Name your fields and inspect the preview. A product name, a price and a link should stay in their own columns. Adjust selectors or the read mode if the sample contains the wrong value. Preview data is not the same as a saved collection run.
Export a collected result
Collect the page, then export CSV or JSON. CSV protects spreadsheet cells from formula injection. Keep a copy of important exports: browser storage may be cleared, and uninstalling removes extension-local records.