To be able to download time reports to Excel, you first need to open the page Time Reports in the menu to the left. Then you simply click on the button Export at the top right corner and choose Excel.
The file will be immediatly downloaded to your computer. In case you want to download it again, you can find the file on the page Files in the menu to the left.
Note that the file will contain the time reports created during your chosen time period. To change the time period click on Interval before downloading the file.