The SRX only supports pppoe authentication on models using the dsl modem card and not on ethernet interfaces. You will need to put the carrier device into bridge mode or get a bridge only modem from the carrier.
Looking at the Orange site, it appears you need to contact customer support for a bridge only modem as there does not appear to be bridge mode on your model.
https://communaute.orange.fr/t5/ma-connexion/Mode-bridge/td-p/510016