Hi Alice,
Thanks for submitting a ticket. I am sorry to hear that you had problems uploading a source file via WikiRate.
The error can happen because some websites include flash animations and window pop-outs that prevent the page from being converted to a PDF file via our platform. The workaround is to save them as PDF files and then upload them as a source.
Please see this guide to find the steps to follow depending on your browser: https://wikirate.org/Saving%20a%20webpage%20as%20a%20PDF
Do not worry. It is easy!
Let me know if you have any questions.
Best regards,
Lucía