Hello ​@sarinme94 ,
You will need to use dynamic blocks to send PDF files via API. However, this feature is not supported on WhatsApp and Instagram channels.

This article from Manychat provides a general explanation of dynamic blocks and includes a link to the documentation, where you can find more details:
https://help.manychat.com/hc/en-us/articles/14281268533788-Dev-Tools-Dynamic-block
 

So we cant send pdf files to user using api?
Some other applications are having that feature.
I have tried the same in some other . Using api i can send pdf files on whatsapp

Unfortunately, this is not possible on WhatsApp and Instagram channels. You can send images, but PDF files are not supported. Below is a section from the documentation:
 

Oh no, so any other solutions. Using external extensions or something.  I have account in manychat but using facebooks api or something? Previously it was there to send whatsapp message from manychay i believe

Hi, ​@sarinme94!

I see you're trying to send it via WhatsApp...

The API documentation is split in two:

• The first part (https://manychat.github.io/dynamic_block_docs/) is just for Facebook Messenger.
• At the top o the page you find the link to other channels: https://manychat.github.io/dynamic_block_docs/channels/

And there you find the information that "Sending files is not supported by WhatsApp and Instagram channels”:

https://manychat.github.io/dynamic_block_docs/channels/#:~:text=Sending%20files%20is%20not%20supported%20by%20WhatsApp%20and%20Instagram%20channels

I've posted it as an Idea here in the community: 

Vote for it, so Manychat's Product Team sees it's something more users would like.

A workaround could be using Manychat's External Request Action to get the file URL via Webhook/API and send it as a text variable.

Hope it helps… 

text variable is not a good option. We need to send the invoice pdf to the customer instead of sending a link as the file

I feel your pain… also had the same frustration.

For now, there isn't a way to make it work using Manychat. I've posted the “Idea” just now, because I've thought it existed already (but there's only another mentioning to make the same with audio).

The alternative is using variables/URL or finding another tool that already has this option. 🫤