You cannot directly download a candidate undertaking certificate for JOSAA 2024. However, the Joint Seat Allocation Authority (JOSAA) provides a format  you can use to create your own undertaking.

• Visit the official JOSAA website
• Click on the " Certificate Format " link under the " Information " section.
• Scroll down the page and look for " Undertaking for Caste Validity.
  
  This page will provide the format for the undertaking certificate. You can copy and paste the text into a document, fill in the required details, print it, and sign it.
  
  https://engineering.careers360.com/download/ebooks/josaa-what-you-need-to-know
  
  I hope it helps!