If that TV Box reads media files… I would think you could just rsync them to a USB stick (is that even possible?). Does the TV Box have some sort of filesystem that you could currently ftp, ssh into etc…?
Oh, reads them from the PC, I see (typing as I am viewing your most awesome graphic!). So, I don’t even know what Freemi is. Ah, connect to network drives on the PC. So there should be no issue if it’s reading from the PC in an assigned directory???
The encryption part I would think could easily be rclone. Install it on the server, install it on Windows 10, even install it on your dog!!!
Then you got the files going to a readable location for your PC to Freemi-mabobber and all is decrypted and well via your rclone on the PC decrypting the files. Then that Freemi-thingy (in theory) would be able to handle playback to your very Basic TV!!!
Oh and also, no HDMI input/output on the TV/PC? Moar derpage. Of course you do, this is just your setup… ok ok.