PDF export from local PC
You can make a PDF with embedded fonts that were used in a diagram by using the "Print" function and printing to PDF on your OS or browser (Google Chrome, etc). The "Print" function is available in the toolbar on the left. You might need to change printing settings to fit the diagram content within a page, such as by adjusting the margin setting.
Reference (Google Chrome - any OS)
Choose "Save as PDF" for the destination option on the print dialog.
Reference (Windows 10 - any browsers)
Choose "Microsoft Print to PDF" as a printer on the print dialog.
Reference (Mac - any browsers)
Choose "Save as PDF" on the PDF pop-up menu on the print dialog.