If you require to upload a PDF file to Salesforce, please follow the below instructions:
Illustrated in the image below is an example of a flow that receives a PDF file via a REST API, converts it from byte data to byte data using the Byte Group mapper step and sends the file to Salesforce using the Salesforce Content Version destination step.
The flow takes in two input parameters for the document parent Id and file name that will be used when uploading the file to Salesforce
A Pass Through reader step is added as the reader step. Thereafter, add a Byte Group mapper step where the Input Mode and Output Mode are both Byte as per the image below. The Combine step is added to batch the data from the file before it sends it to Salesforce.
The Salesforce Content Version destination step is used to upload the file to Salesforce. The Parent ID file and Path On Client field can be inputted by referencing flow parameters as shown in the below image.
The flow can be executed from a number of sources such as a REST API where the Callback URL is used on the PDF writer step (refer to the image below) or from another flow that creates a PDF file.