Please confirm that you have enough space on your system to meet the minimum requirements that the game you are hoping to play demands.
We have several articles on our Support website that outline minimum requirements for most Ubisoft games that you can use as a reference. The Ubisoft Store also has this information available on the product's page.
If you have enough space on your system and are still receiving this error, try to run Ubisoft Connect with administrator rights next and see if the download continues.
Our team is here to assist you if you continue to have issues with your game download. Please contact us with the error code you are receiving, the troubleshooting you have tried, and details about how the download is behaving at the time of your contact so we can jump right into getting you back into the game.