Apps to the rescue to record from USB on android?

I tried to record sound to a Motorola G5 through a USB sound card connected via an OTG adapter. Didn't work although playback worked. On a Nexus phone playback didn't work either.

It turns out USB sound card support is skimpy even in newer versions of Android.

One solution that is recommended on a forum is USB Audio Recorder - Apps on Google Play. The app has its own USB driver and their site shows support for a lot of phones and a lot of audio interfaces, including some really fancy ones.

But its free version available from their web site behaves lik a zip file on the phone, instead of as an apk, despite having the right suffix and being in the same folder as other working apks that can demonstrably be installed, downloaded with the same program.

I found also n-Track Studio Music DAW - Apps on Google Play but it wants to read my contacts. I'll see if I can turn that off and see how it behaves.