Copying your workbook link just means copying the URL for the workbook you're working on.
I would recommend posting this query in the Cohort channel you're a part of. You will get a response from the team there. If you have any issues about the product, please let us know here!
Hi Ayush,
Thank you for reaching out to the support team. Can you please let me know what Cohort you are a part of? Which assignment are you having issues with submitting?
You have until the Wednesday after your cohort ends to submit all assignments. Students get 2 full weeks total to complete and submit their work.
If you can't finish in time, you can switch to a future cohort using the Cohort Application Update form and your progress will be saved.