Hi Juan,
Thank you for contacting Syncfusion support.
No, HTML converter do not have support for inserting page numbers in place holder on HTML source itself. HTML to PDF converter internally make use of Blink rendering engine for converting HTML to PDF. So, the converter will preserve the PDF document like how the input HTML file is preserved in web browsers.
After the conversion we can add page number using PdfFooter, please refer below link for more information. But we do not have support to include the page numbers in HTML source itself.
Please find the UG link, kindly include this in the provided response.
Please let us know if you need any further assistance on this.
Regards,
Sowmiya Loganathan