Hi there!
I’m afraid that this is a general pack issue, it’s Coda’s single request limit, discussed here and also here
I think the best solution would be to store the PDF temporarily on the server and expose it with a private URL which Coda could ingest, but for security and privacy reasons, nothing is currently stored on the server
So while this is possible I’m afraid it’d be a pretty major update that won’t happen anytime soon, sorry about that. In the meanwhile I’ll apply for an increased single request limit for the PDF pack, which could help a little