The error as it shows in the log is that the version you have installed is 2.0.4, and you're trying to download 2.0.6, both are in different URL's, that's the error - URL mismatch -.
Maybe you need to delete the Lazarus folder, so it downloads it again, but don't delete your settings folder, maybe it get's upgraded from 2.0.4 to 2.0.6-