Disk space
Before installing, Salience checks the folder you chose has enough free space, and shows both the required space and what's free on that drive. This is the same check that runs before the one-time sound engine download.
Two real options if it doesn't fit: free up space there, or point setup at a folder on a drive with more room. Installs also need working room beyond the final size while files unpack and verify, so the check estimates total space needed, not just the final footprint. Still stuck after that? See Repair and setup.