How To Get a gps map for addzest NAX 010 series car dvd navigation system

[Keidi]

Hi all,
My used Toyota came with an addzest multi-access dvd navigation system
NAX010 series.The problem is that the DVD that accompanied the system-labeled road explorer dv6.0. Only has a map of Japan whereas I need a Map of Kenya where I live.
Both clarion and addzest websites do not seem to have the map or even a product page.
And a check on wikipedia states that there are many map formats and it's hard to know which is compatible with this unit

Any assistance highly appreciated.