Wow, that is a very, very nice gift! The Eigenharps are all fantastic, and the Tau is my personal favourite among them.
Don’t worry about not having the USB stick. The contents of that is old and not very useful anymore anyways. The latest official EigenD software release is old, and it makes much more sense to grab the Community version maintained mainly by TheTechnoBear.
This is a nice summary of where to find stuff:
It has been a while since I last did a clean install, so check the install instructions in the EigenD community release. But if I recall correctly you will need the official Runtime and Drivers.
Once those are installed, then install EigenD Community 2.1.7 and you should be ready to go. There is an optional Resources download with some VST plugins, audio loops, etc. I don’t find it useful personally, but nice to know it exists, I guess.
Note: EigenD is a very powerful and flexible piece of software, but can also be very confusing at first. To get the most out of your Tau you will might want to dig in and create setups specific for your use-case. I don’t know if you are very tech-savvy or not, but be aware that this takes a bit of effort and patience. If you need help getting to grips with things, I’ll gladly do a video session. I’m not an expert, but I (sometimes) use EigenD on Windows and I own a Tau. You will discover that there are a lot of helpful people in here. So for specific questions fire away.
Tip:
EigenD can host plugins, but most of us(?) prefer to send midi or osc out of EigenD and into our DAW/VST of choice. One option is to check out Madrona Labs Aalto/Kaivo. These plugins can receive high-res osc data from EigenD, bypassing midi altogether. There are lots of good options for MPE-midi VSTs. My personal favourite is Roli Equator 2. A good UI that is fast to patch in, tons of useful presets and a synth engine that can provide a wide range of sounds.