Using PDF Files with Message Received Trigger in Lindy Support

Hello Lindy support, I am creating an agent with the message received trigger and I want to loop through PDFs and extract the text from the and then end the loop. However, when I initiate the message received step and try to upload PDFs, the agent is unable to support PDF files and wants a CSV instead. Is there a way me to upload PDFs using the message received trigger or should I be using a different trigger/action altogether?