That flashcart seems to be a gateway clone. It comes with 2 cartridges, one to play DS roms and another to play 3DS roms. Both work only on 3DS firmware up to 4.5; Newer firmwares are not supported. If you want to support newer firmware for DS roms, there's a way: you must install this CIA file to your sysnand. The problem is that 3DS roms won't work anyway. I suggest you keep on 4.5 firmware forever, where everything works.

 

There are many flashcarts that work. I own and can recommend the SuperCard DSTWO. Remember that it can't play 3DS games, only DS games are supported. Supercard DSTWO also supports SNES and GBA games.