Ionic package build IOS Error

Hi, I am trying to use ionic package build for IOS using ionic pro and legacy account, but its showing me below error.
[ERROR] Sorry! The configured backend (pro) does not know about ionic package .
Let me know the package build process steps. How to do package my ionic 1 project. Thanks in advance.

Docs for Ionic Pro Package are here: https://ionicframework.com/docs/pro/package/

Thanks for your response. I can able to login and SSH setup, then I give “sudo ionic package build ios --release” after that only this error showing
ERROR] Sorry! The configured backend (pro) does not know about ionic package build.
You can switch backends with ionic config set -g backend (choose from
pro, legacy). How to do package build?

Read the link I posted.

I try to convert IOS certificate (PEM to .p12) format, using (openssl pkcs12 -export -inkey keyname.key -in ios_development.cer.pem -out Certificates.p12) but getting below error ,

Error opening private key keyname.key
140735534773128:error:02001002:system library:fopen:No such file or directory:/BuildRoot/Library/Caches/com.apple.xbs/Sources/libressl/libressl-22/libressl/crypto/bio/bss_file.c:255:fopen(‘keyname.key’, ‘r’)
140735534773128:error:20074002:BIO routines:FILE_CTRL:system lib:/BuildRoot/Library/Caches/com.apple.xbs/Sources/libressl/libressl-22/libressl/crypto/bio/bss_file.c:257:
unable to load private key