"Unable to pay as your account may be at risk 1138" error in PUBG on iPad

Error 1138 -> looks like a payment error.

You may need to have a payment method on file, even if the app you want to download is free.

Check which payment method you have on file 

See also -> Payment methods you can use with your Apple ID

Payment methods you can use with your Apple ID – Apple Support (UK)

You can also use your Apple ID balance as payment method: Add money to your Apple ID balance

Add money to your Apple ID balance – Apple Support (UK)

You can also contact the app developer -> How to contact an app developer – Apple Support (UK)

We are all other users here and do not have access to any accounts. Your post also does not make sense - no idea what "at risk 1138 fix" is.