Yes, this is possible. First, make sure you backup your files and database, though.
Next, upload the archive package (downloaded from the web site) to the root of the web server where you want to handle the "installation." Once done, you can connect to your web server via SSH and navigate to the directory where you uploaded the file. Once in this directory, type unzip Dolphin-v.7.0.0.zip and the web server will begin decompressing the archive, which will immediately prompt you to select what option to take for the multiple files of the same name, which you can just choose to replace.
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