You can use almost any navcore you like on this model.
For eg. for my GO 730 I use 9.051 which you can download from here:
Best NavCore for Go x10, Go x20 and Go x30
The latest official navcore for the GO 530 is 9.465 which you can either get from TomTom HOME for free, or download it from here:
Navcore 9465 for GO X20, X30, X40, X50, One IQ Routes, XL IQ Routes, XL Live, Xl IQ R