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In Salesforce go to Setup.
Search for Users > Permission Sets.
Create a new Permission Set:
Give a name to the new permission set (for example: Set audit Fields Permission Set) and save it:
Once it is created it will be open for editing. Scroll down and click on System permissions:
The System Permissions page will be shown. Click on Edit:
Find Set Audit Fields upon Record Creation and check it:
Press Save to save the permission set:
Confirm the changes by pressing Save again:
Assign the DocuFlow service account to the permission set by pressing Manage Assignments:
Choose Add Assignments:
Select the service account you want to assign the Permission Set to and press Assign: