If the server runs on Windows, I guess you have to give access to the machine account the Domino server is running on.
Most Windows administrators prefer creating a special user account for services like Domino.
To expand on Marcel’s comment, the ‘local system’ account does not have network privileges - it cannot access the network shares. The Domino service has to logon using a Windows account that has write access to the network share.
Subject: Domino running as Local system in windows is elevated
From my experience, domino running as local system in windows is elevated. Like, I try to run an .exe file via a script and triggered in domino and runs without any issues (without having to specify run as admin in the script). Only in linux do you have to specify folder permissions because then it has to run as a specific user. from what i know local system user can write to any folder on the machine. anyhow you can capture folder permissions error quite easily in the agent log.