I've tried both [fn:: ... ] and \beging{quotation} ... \end{quotation}. Neither of them exports the quote block inside the footnote. I've also used #+BEGIN_EXPORT latex ... #+END_EXPORT and had the same results. There is also an old question about this topic but there is any answer.
My org-mode version is 9.3.8 and I use org-plus-contrib. My emacs config is similar than scimax compiled with modules.
Here some usefull links
Thank you all in advance
You can get a quotation environment within a footnote by using the @@latex:...@@ construct, as in:
This *is* very interesting [fn:1:But not as interesting as it could be: @@latex:\begin{quotation}@@This would be a quote from somebody funny or smart.@@latex:\end{quotation}@@]. And we need to look at it.