Is it possible that the cloning quality is much higher on the website than locally? Isn't the method supposed to be the same?

[Mixomo]

Doing a voice cloning using the Fish Audio website, gives the expected results and the voice is identical to the audios provided. However, doing the same in local, the resulting voice has nothing to do. At most a slight resemblance with the timbre, but not much more. It does not respect the accent.
Is there something I am doing wrong?
How can I replicate the results of the web page, which are displayed as instant cloning? Do I need to do a local fine-tuning? I don't see much sense in it, since it would not be instant cloning...

Thanks in advance!