Great question — answering as the UphillTech team:
The anchors shown require drilled holes . They cannot drill themselves into a plastered wall. Use a drill and bit to make pilot holes. from https://workboots.com/tradecraft/drill-bits-buyers-guide
Full answer by DrMoishe Pippik: https://diy.stackexchange.com/a/330905 (CC BY-SA 4.0).
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