I used it in years past, but it's been quite a while.
I tried to use it last night and it wouldn't see the MIDI ports, either when connected directly via USB from the iPad to the Tetra, or using a USB<->MIDI interface with the iPad and connecting to the MIDI DIN connectors on the Tetra.
I see the app hasn't been updated in quite a while, and I'm trying to use it on a current(ish) iPad Pro with iOS 17.
Soundtower still advertises it on their site, so I would hope they're still supporting it, but maybe not? I sent them an email, maybe they'll respond, but in the meantime, I'm wondering if this could be user error.
I think I have all the settings correct:
MIDI Channel All
Clock Internal
MParam Send NPRN
M Param Rec All
MIDI Control On
MIDI SysEx On
If I use a different app on the iPad, I can see the Tetra's ports and send MIDI from the app to the Tetra, but not the Soundtower app.