Collabora Online: info about "Save As" functionality

Hi Friends,
I’ve installed Collabora Online 6.4 on Nextcloud for my own italian association.
My question is: how enable the Calc CO exporting “csv” ability as described here: Importing and Exporting Text Files

On my own installation (debian native, no docker) i’ve no format options in the “Save As” window, how you can see below:

image description

What I should do for enable “filter” (?) ability? I’ve not found any other documentations around this issue.

Many thanks!