SD Card game corruption

[UchihaSasuke23]

I need some help, I bought a new kingston micro sd. It is 8 gb. Im still confused if im gonna put it as an internal storage or portable. I first tried to put it in portable. Ive transfered the only iso then when im gonna play it. It cant be played because ppsspp said it was corrupted. Icant play any games in my sd card it always corrupt. I tried to put it in internal storage but I can't transfer any files/iso. And I can't even install any game because it automatic goes in the local storage and I can't transfer it. I need help how can I play it in as card I don't want to waste money