Rule reminder
With modal verbs (dovere, potere, volere + infinitive), the clitic can go before the modal or attach to the infinitive: 'Lo devo fare' / 'Devo farlo'. In compound tenses (passato prossimo, etc.), the clitic precedes the auxiliary: 'La ho comprata' → 'L'ho comprata'. Past participle agrees with the clitic.
Quel documento, … devo firmare entro oggi.