Files with m4a extension can contain various audio stream data types. There are m4a files that contain straight ALAC or AAC data, and these should work. Others may contain other data, e.g., DRM-protected data, and these fail.
„Got“ how? Did you download streaming files? This is obviously unsupported (not to mention not allowed) and I wouldn’t be surprised about problems. They may well be DRM‘ed if it wasn’t stripped.
It’s definitely strange that the codec is FLAC and the extension m4a, as well as reporting „variable bitrate“ FLAC files normally have a „flac“ extension and no variable bitrate.
As the community has explained, this is not a Roon issue — the files appear to have been downloaded from a streaming service using a third-party tool, which resulted in files with an incorrect format. Roon is unable to play these files as they are not in a supported or valid format.
We are unable to assist further with files obtained this way. If you would like to use Roon with Tidal content, please use the official Tidal integration built into Roon.