Joomla does not know about your Download ID. Either you have not entered it or you bumped into a known issue in Joomla — apparently addressed in Joomla 4 — which makes Joomla “forget” the Download ID. Please follow these instructions in our documentation: https://www.akeeba.com/documentation/akeeba-backup-documentation/update.html#dlid-change-after-update
Important note: if you want further support please do NOT post your Download ID or a URL containing it. If necessary, give me only the last four digits of it; I can check your user account to see if it's likely to be correct or not.
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!