Roon should be able to read the Sooloos files, just add the music folder location in the settings, storage tab, so if you are running Roon core on a PC and your music is on the NAS in a shared folder called Music then in the Roon storage tab add a network storage location with the path ‘smb://nas name or IP/Music’.

For example ‘smb://192.168.1.65/Music’ it is a good idea to fill in the user and password fields, these are the NAS Admin user and admin password, defaults are Admin admin.

To see the names of shared folders on the NAS look in filestation on the NAS web interface, worth bearing in mind that once Roon has added all the files you can do a full export to a disk where all files will be exported in native format eg the format they were imported in.

Edit Just seen you are running Roon on the TS251, this is quite underpowered for Roon so may not perform quite as you hope.