Hi Nouama,
The Marketplace one works with only Native apps! Since you are testing this with the PWA version this component will not work, unfortunately!
Knight from Visual Dev Studio and Steven from Pragmaflow created two QR Code Scanner components that work with PWA’s! ( Not sure if the Pragmaflow one works still because Pragmaflow team does not maintain them in the present but you can try the Knight’s one )
https://forum.adalo.com/t/qr-scanner-does-not-read/25876/2?u=dilon_perera
Thank you