404 error after payment

I have followed all the configuration steps, however, after the client pays in Paypal, he is redirected to a 404 page within my site (and the payment is not processed).
The url with the 404 error has ths structure
https://www.tashay.de/de/wc-api/paypal_plus/?paymentId=PAYID-XXXXXXXXXXXXXXX&token=EC-XXXXXXXXXXXXXXXX&PayerID=XXXXXXXXXXXX

Does anyone know what ir wrong?

Thanks

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