Permission failed when trying to download app

So recently, I’ve been wanting to download PVZ 2 on my IPad. I had it on another device that had broke before, but that isn’t really important. I went to download it, put in my password and asked for guardian permission to download it. However, since I’m the only person in my family to own an Apple product, (my guardian has an Apple ACCOUNT, but not a device. Im not sure if this would affect my issue.) I instead decided to go with the “in person” option. My guardian put in their gmail and their password, but when they pressed enter, an error happened. Verification Failed. They tried again and again, and it just wasn’t working. I restarted my device, and even then it wasn’t accepting it. What could have been causing this? (For extra context that might also be causing an issue, my guardian changed my password recently, because we both forgot what it was when I went to download the game.)