When using a Velixo function, instead of a result, an error is displayed: "This function is not supported by your version of Excel..."

The most likely reason would be that the installed version of Excel is not recent enough and does not support dynamic arrays.

See Dynamic Array Functions Pre-Requisites for steps in testing your installation of Excel and upgrading to version of Excel 365 or Excel 2021 which supports dynamic arrays.

As of July 2020, Dynamic Array functionality is available to all Microsoft 365 subscribers.