The Game Boy Advance's buttons are mapped as follows:

💡 Moving to another emulator?
Make sure the downloaded .sav file has the exact same name as your .gba file (e.g., Pokemon.gba and Pokemon.sav) and place them in the same folder.then open a incognito mode page and import your save there to test,and remember always keep a backup,if you want to import a .sav or .srm remember to uplaod the save before loading the rom