What do I need to play VB3m from my Midi keyboard?

MIDI INPUT

You need to connect your Midi keyboard to your mobile device, and for doing so you need some accessory. If your device is an iPad or iPhone, first thing you need is the so-called Camera Connection Kit or the USB-C to USB adapter, and you should buy the original accessory from Apple or it won't work. 

Here's what you're looking for: Apple USB-C Digital AV Multiport Adapter

The accessory makes it possible to connect a USB peripheral to the mobile device. Actually, speaking in USB terms, in this case the mobile tablet or phone acts as the "host" and your keyboard controller is the "device".

If your mobile is an Android phone or tablet, you need an OTG (On-the-go) adapter, with USB-C or MicroUSB port according to the port your mobile uses. This accessory may come with some hi-end mobile, or you can buy one at an electronic supply store for something between $2 and $10. Here's an example:
https://www.samsung.com/au/support/mobile-devices/what-is-an-otg-on-the-go-cable/

Please note: not all adapters are of OTG type, make sure it's OTG, not a simple port converter.

Now, if your keyboard controller has built-in USB interface, it should also be a "Class Compliant" unit or it won't be seen by the host. Any modern keyboard manufactured after 2010 should be class compliant. How do you know if it's class compliant? Just connect it to your computer, possibly a Windows computer. If you don't need any driver to use it, it will also work with your mobile. Some workstations have options to configure the built-in USB-Midi connector. For instance, the Roland Fantom or RD-2000 can run the port in "Vendor" or "Generic" mode, where Generic is the class-compliant mode that lets your mobile "see" the device. Always refer to your controller's documentation for more details.

In case your keyboard doesn't have a built-in Midi-Usb interface, but only features the old DIN-5 Midi ports, you'll need an external Midi-Usb Interface. If you have to buy a new one, make sure it's modern and is of type "fully class compliant", i.e. "plug and play" or "driverless".

If you wish to test your Midi stream, open Chrome from your mobile and visit this URL: https://www.gsidsp.com/MidiMonitor

Pay attention: some modern workstations, synths, digital pianos feature both the host and device port, usually the host port is the USB Type A (rectangular) and the device port is USB Type B (square). You should always use the device port because, as stated before, the phone/tablet is the host and your keyboard is the device. You cannot use your recharge cable to connect your mobile directly to the host port of your workstation, it will just not work.

Also worth noticing is the fact that not all self-powered USB controllers can be directly connected to an Apple mobile device. If the device isn't directly supported (i.e. authorized by Apple), it's likely that you'll see the error "This device is drawing too much current". The controller should have its own power supply, or another workaround is to use an external powered USB Hub that will supply power to the controller.

Once everything is up, launch VB3m and play. If you still can't get any audio from the App, make sure the Midi channel sent by your keyboard matches the channels received by the App, also make sure that you can get audio out of your mobile.

AUDIO OUTPUT

Getting audio output from a modern device can be trivial, since they removed the good old headphone jack from almost all devices built after 2022. We still have the USB port that carries both MIDI and AUDIO, but we need to find a good and affordable solution.

First thing to keep in mind is that BLUETOOTH AUDIO is not an option, as it introduces a terrible latency between 2 and 5 seconds, so do not use Bluetooth audio devices (headphones, speakers, etc.) if you expect real-time audio.

If you don't have one yet, a good solution is to buy a mobile-ready Audio/Midi device, a box that offers both Audio and Midi connections all-in-one, that terminates with a single USB-C cable that goes straight into your mobile device. There are many, and most are quite affordable. Avoid chaining too many adapters, avoid unknown quality accessories, or something will surely go wrong while you're performing. Check with your dealer and buy a good interface.