Error when trying to open saved Pages doc on my iPhone's iCloud

I have saved a Pages doc in my iCloud when writing at home on my Mac. Now i am outside trying to open it on my iPhone and although i can see the doc listed by file name i get an error when i try to open it. Are there solutions for this? Thank you.

MacOS and iOS up to date.

[Re-Titled by Moderator]

Original Title: Pages in iCloud er