If you are using a PC/Mac, an OTG cable is not required. Just a conventional USB-microUSB cable (not provided with the unit)
If your device does not include a USB-C connection, use an OTG cable adapter - USB (female) to microUSB - so you can connect it to the amplifier. One end of the microUSB must be connected to the Android device, while the other one must be connected to a conventional charging cable (USB-microUSB) and then connect it to your Avant. Make sure that the OTG cable is connected straight to your Android device, not to your Avant.
Asuite is compatible with Avant X, Avant 9 and Avant6.
The operating system must be Windows XP, Windows 7, Windows 8, Windows 10 or MacOS and the Java software version 7 or higher.