For storing music from your disc collection, you can use ExactAudioCopy with a USB CD-ROM drive connected to your PC to rip CD audio. Then store all that music in a folder and share that folder over your local network. The Marantz should be able to find the shared folder and play music from it.
If the shared folder doesn't work, Windows has a built in DLNA server. Just do a search for 'windows dlna' to get instructions on how to enable it. Make sure the audio files are in the 'Music' directory.
Bluetooth uses lossy compression to send audio to the 8006. That’s not ideal for Tidal. If possible, try switching to UPnP instead. That will stream uncompressed audio.
If UPnP isn’t an option, then directly connecting the phone to the 8006 would get you the same sound quality.
Don’t worry about buying a fancy USB cable. As long as you don’t hear any dropouts or glitches, the data is getting from your phone to the Marantz intact.