Since the game is new, it's not going to be on any database so nothing auto-detects the save type. It looks like NSUI 27 doesn't let you manually set it, but I found the beta 28 here which does. You could also use the old Universal GBA VC Injector which also lets you choose the save type.
GBA Tool Advance patches the rom to support SRAM, but that isn't necessary since the game already does. Your problem is getting the VC Injector to use the correct save type.
In VBA-M you also have to manually set the save type to SRAM by going to Options > Gameboy Advance > Configure. Set the save type to SRAM 128k before opening the rom and it should work 
though I'd recommend switching to mGBA.
Hope this helped!
