Hi John,
Just to be sure, are you referring to the following as the UDB4 quick start guide:?
In any case, the UDB5/6mini can use the latest version of the
MatrixPilot software, with the MatrixPilot-udb5.X project. The minis have the same basic hardware design as the UDB5, schematic attached and share the exact same software. Some of the unused pins are not available on the minis and there is no EEPROM, which most users are not using. The connections for I2C for such things as a magnetometer, are solder pads on the underside of the board.
If you have been already programming a UDB5, whatever version of the MicroChip tools you are using will work with the minis.
Although running the compiler will eventually trigger a warning that you do not have a license, don't worry, a license is not needed.
Best regards,
Bill Premerlani