Currently it doesn’t support ticket attachment. We’re working on it, and it will be available very soon inshALLAH. But before that we need to test things in a larger phase, so it will take a bit of time.
In the mean time, you can use Stardard WordPress media uploader (in admin end only) for uploading PDF (or any accepted file types) and can attach the file URL anywhere inside the textarea.
Screenshot: http://prntscr.com/bx8zqp
Additional information:
https://codex.ww.wp.xz.cn/Using_Image_and_File_Attachments
