Just install the plugin, active, setup api key, go to post edit screen, click dropbox button, insert file from dropbox into wordpress editor.
This section describes how to install the plugin and get it working. e.g..
Navigate to 'Add New in the plugins dashboard.
Activate the plugin on the Plugin dashboard..
Activate the in the Plugin dashboard..
Upload the directory to the wp-content plugins directory.
Activate the in the Plugin dashboard...
Go to Dropbox developer portal and create app https www dropbox com developers app, choose app type drop-ins type and follow the steps, copy the App key...
Also, I think the developer should describe the process on getting API Key on DropBox, for some users, this will may be confusing.
Browse the code, check out SVN repository, or subscribe to the development log by RSS...
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