I didn’t know this either! Just seen their site, they have several packages: https://www.zrythm.org/en_GB/download.html

I think it is fair enough that they need to make money somehow but looks like they have only made £155 in November which is a shame. I have been a low-level donor for Ardour for 12 years now, and you can see they make something like £4000. I will check out Zrhythm properly as they obviously put a lot of effort in.

Got to say I strongly disagree, I have used Ardour and other DAWs extensively. Ardour is a very good DAW but it’s MIDI capabilities are still improving. Zrhythm and Ardour came from different angles and seems like they are both becoming more modern.