How to access messages from iCloud Storage

Good day all,

My mother died three years ago and when that happened I took over her iCloud account so I can sign in to her iCloud in Safari. However, I cleaned, reset and sold her Mac and her iPhone so I have no access to these devices.

I can see 1.3 GB of stored messages in her iCloud storage. My brother and I would like these messages. Is there anyway to retrieve them?

Thank you,

James