I have problems when compressing to Flac

Flac doesn’t support compressing files on a network share (e.g. \\computer\share). In this case you will receive an error when EAC tries to compress to Flac.
As workaround you could map the network share to a drive letter and use the drive letter as target for your extractions within EAC.
You find more details here: https://support.microsoft.com/en-gb/help/4026635/windows-map-a-network-drive