I have a Synology DS212+ with DSM 6.2.4-25556 Update 7
running on it.
I cannot install any RoonServer package. It gives me the error: “Dieses Paket wird auf der Plattform von DiskStation nicht unterstützt oder ist nicht kompatibel mit der aktuellen DSM-Version”
as mentioned you need a NAS with a compatible 64-Bit CPU.
If you might be planning to replace your unit and stick to the same manufacturer I strongly recommend to choose one of the well-equipped Synology NAS (CPU- and RAM-wise). Ideally DS723+ or DS923+ but DS720+ or DS224+ also do a decent job (with RAM extension) for medium-sized libraries. According to my experience most of other affordable Synology, even the Celeron-based ones, are underpowered for a smooth roon experience.