Midi, Soundflower, and internal record options

As far as I know, Soundflower has not been updated since Big Sur and was never updated for Apple Silicon. It appears to me to have been abandoned.

If you want to stick with freeware, the replacement would be Blackhole Audio. I don't advocate it, but it does work and many people use it in conjunction with Audio Midi Setup to create aggreate and/or multi-output devices to route audio between apps.

I tend to suggest Rogue Amoeba Loopback because I think it's a more capable and reliable audio routing utility. It's a commercial product that you have to purchase.

Depending on your needs, you might consider Screenflow to capture audio & video simultaneously. I use it and it works great.

My first reply was based on your inquiry about Soundflower, assuming you were asking how to capture audio at the same time you record screen video with QuickTime. QT by itself can capture video or audio but not both at the same time; that's where Soundflower and now BlackHole Audio come into play. They can be set up to route audio into QT to be recorded by QT along with the video. This is a DIY method of capturing screen video & audio simultaneously. It's popular because it's "free."

Loopback is an audio routing utility that performs functions similar to what Soundflower & BlackHole Audio do, but it has much more capability than either of those freeware apps. Audio Hijack is an audio recording app, it would not be useful for routing audio for your purposes.

EaseUS is a desktop screen recording app that can capture video & audio at the same time. I'm sorry to hear you ran into a problem with EaseUS. It sounds like you purchased it directly from EaseUS and you should have received a license code via email that you would have had to enter in the app to authorize your use. Sounds like that didn't happen and the app then prompted you to pay as if you had never purchased it.

Screenflow is designed for video capture (desktop screen recording) but it also has a built-in video editor. You do not need to use the editor. In fact, so far I have only used it to capture streaming video and export/save to disk in a number of different formats including MP4.