Mine was incredibly simple to set up, I had it ready to go in under 5 minutes. Take it out of the box, and you need to put the feet on (2 bolts, allen key included in box) and then it's free standing. I then put the cassette on - there isn't one already fitted, but I put a spare 12-25 on that I would normally use for commuting - this needs both a cassette lockring tool and a chain whip - the freewheel doesn't stay in place like it does on a bike so you need both.
Once I'd done that I realised that my steel road bike won't fit on the trainer - the stays narrow too quickly unfortunately, so I'm using my old 26er MTB instead - not really much difference for a trainer I don't think.
The Flux is setup with Zwift and provides cadence and power (Zwift sorts out the speed part) and I use an Ant+ dongle that I got from amazon for around a tenner for the HR strap. So I just use ant+ to connect to my PC instead of bluetooth.
I'd use Zwift over Garmin connect to upload to strava personally, as you'll get the GPX trace as well, you can always delete the garmin activity if needed. That being said I don't use the garmin at all when on the trainer as the information from Zwift on screen is plenty for me.
Quite happy with the Flux so far, although I've only really done one session. I need to check out the power output against my power meter, as it felt really hard last night for the power it said I was producing - could just be my legs yesterday though!