Mirroring between iMac and Synology NAS

Dears,
Just arrived here, and the software looks powerful.
However, I think I miss the logic behind it (the way the software "thinks") to really understand the way to exploit it.
What I want to do is create a real-time mirror from a picture folder to a NAS.
The goal is that a Smart TV (or any home/mobile/... device) can visualize the pictures as soon as they are produced/removed, without having to access the Mac itself.
So I selected the iMac folder, and selected the steps:
If "any" ... :
Subfile/folder count "did change"
Size "did change"
Do the following:
Sync into folder "JPG on NAS"
For a reason I don't understand, it doesn't work.
Even the "preview" is not returning any info - or maybe it is me who cannot use it.
Any help to achieve the task would be welcome !
Just arrived here, and the software looks powerful.
However, I think I miss the logic behind it (the way the software "thinks") to really understand the way to exploit it.
What I want to do is create a real-time mirror from a picture folder to a NAS.
The goal is that a Smart TV (or any home/mobile/... device) can visualize the pictures as soon as they are produced/removed, without having to access the Mac itself.
So I selected the iMac folder, and selected the steps:
If "any" ... :
Subfile/folder count "did change"
Size "did change"
Do the following:
Sync into folder "JPG on NAS"
For a reason I don't understand, it doesn't work.
Even the "preview" is not returning any info - or maybe it is me who cannot use it.
Any help to achieve the task would be welcome !