Send SMTP email with multiple attachments

Hi, I am not into computer field and I am using the cloud version of AP. I have setup a SMTP piece to send an email with a couple of pdfs attached to it (when a trigger is received). I only see one box to add an attachment in (which I understand should be the url to the pdf). But I want to attach multiple files. How do I do that? Thanks so much in advance.

Can anybody direct me in the right direction to achieve this? It seems like the simplest things but I can not figure it out :frowning: