FileDataDropBox

To make DropBoxFileData work you will need a dropbox api key and a authorization token to get the api key you can go to this address https://dropbox.com/developers/apps when you have the api key you will need to generate an authorization token you can use this utility for that

https://github.com/egarim/FileDataDropBox/blob/master/DropBoxAuthGenerator.zip

To get the authorization token use the following command

BitFwks.DropBoxAuthGenerator.exe YourApiKey

Once you have the authorization token you need to add some parameters on the app/web.config as shown below

<appSettings>
    <!-- ... -->
    <add key="DropBoxFileDataDefaultFolder" value="NameOfMyFolderOnDropBox"/>
    <add key="DropboxAccessToken" value="MyDropboxAccessToken"/>
    <!-- ... -->
  </appSettings>
</pre>

Now you can declare a DropBoxFileData as any other persistent property

    DropBoxFileData attachment;
    public DropBoxFileData Attachment
    {
        get => attachment;
        set => SetPropertyValue(nameof(Attachment), ref attachment, value);
    }