If you are using Selenium Library to navigate to the page where you’re downloading the excel file, perhaps a better option would be configuring the browser’s download location and also configuring it not to prompt for download, see this thread for an example of doing that.
Is that Docker container that Jenkins runs a Windows docker container or a Linux one? (most of the time they are Linux but windows ones are possible provided the docker server is also a Windows server) - Remember FLAUI will only work on Windows.
Dave.