If there’s an error, it should email you and tell you what the problem is.
Note that it has to be installed in a completely empty folder or it won’t happen – that includes directories and hidden files like .htaccess. If you made a new folder for it, that shouldn’t be an issue, but if you’re installing it your root directory and already have files on your site–go with a manual install or temporarily move everything somewhere else.
In any case, you could just download it from wordpress.org and install it yourself. Their site has step-by-step instructions on it. As far as the templates go, you should check out the theme browser and style browser at alexking.org. I’m not sure what template DH uses, but that site has a lot more than 50 themes/styles to choose from.
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