What rights are needed for file storage volumes in 1C?

Question

1C

We have three machines:
M1 - a machine with a shared resource
M2 - a machine with a 1C server
M3 - a machine with a 1C client
In 1C, in the settings for working with files, I specify Store files in volumes on disk. I want to create a volume in a resource on M1.
Question one - which user should have access to this resource? The one from which the server is running on M2? Or the one that launches the client on the M3? Or how?
Now let's change the situation a bit. On M3, we connect to the 1C base through an external connection and try to attach files.
Question two - and in this case, which user needs access to the shared resource?
Since I did not manage to attach the files, there is a feeling that the answers to the first and second questions are different.
Unfortunately, this whole system is far from me, it is not controlled by me, i.e. there is no way to quickly try all the combinations. And in general, I would be glad to receive a theoretical justification.
Thanks in advance!
p.s. Thanks to those who replied. Until now, I have no doubt that the server needs the rights to the resource, well, the user under which it is running. But here's the problem.
The configuration is described above. If I work in a regular 1C client on M3, I can add files without problems, i.e. the volume is configured correctly, it is available, there are no size restrictions.
And I have a code that needs to be executed by connecting to the same database through an external connection. The code attaches files to documents.
If the files are stored in the database, then everything works fine - the files are added. But if I enable storage of files on disk, then when I try to attach a file, I get an error:
{CommonModule. AttachedFiles.Module(605)}: Error adding attached file "1234567890.pdf":
Failed to add file to any of the volumes.
List of errors:
Error adding file "1234567890.pdf"
to volume "Volume1" (\\M1\Volume 1C\20170922\):
"Error creating directory "\\M1\Volume 1C\20170922\":
"Incorrect path to file '\\M1'. 161(0x000000A1): Invalid path specified. ".".

Answer 1

the client works with the server, and the server with a file resource. Accordingly, we need rights for the computer and the user on behalf of which 1s works