For API users, the certificate must be uploaded via the GUI (i.e., first change the user type to Normal, upload the certificate, and then change it back to an API user).
The following conditions must be met:
The given API user has only 1 personal certificate.
The request for PDF export must include the query parameter "report-sign=true". If this parameter is provided, the PDF output will be signed, or the API will respond with an error.
Sample URL:
demo.flexibee.eu/c/demo/faktura-vydana/1.pdf?report-sign=true