Does security block access of writing CSV tekst to my NAS? Or is there something else wrong?

I’m working on storing time-series data as CSV files on a Synology NAS. The data is generated by a service running inside Docker (e.g. Node-RED), and I’m trying to write this data to a shared folder on the NAS. Current setup: Synology NAS running DSM Docker container (Node-RED or similar)...