iCloud access issues: forgotten password/passcodes

Oh my where do I even start with this as this has been something I didn't exactly plan on having to write, I'm posting this on behalf of my mother who has had to move onto a brick phone due to unforseen events and this is one of the last things we all need to do to try and get back into as it's been pushed to the side.

The iPhone (not used anymore but still alive) and iMac (that I just managed to log back into using Terminal) are linked to her iCloud account which is the main reason why I'm here.

I am unable to log back into and gain access to all the photos, contacts and subscriptions that are still active on her iCloud account and all that information is vital, especially right now.

If Apple had any sense of technical support, I can give both the iPhone EIMI and iMac serial numbers to check they are linked through her iCloud but I need the iPhone "numbered passcode" and an old iMac password which again, because of said unforseen events, my mother is fully unable to cognitively remember anything to do with those.

The iPhone has been reset by mistake to try to null the numbered passcode which wasn't my doing but the iMac is fully able to be logged into.

The only thing that needs to be logged into and restored is the access to the iCloud account.

I have the email that's used, just no password

I have the iPhone and iMac that was used for said iCloud account.

I need help with this, the situation is quite dire.

Any help would be great and I hope Apple has a really good explanation about this.

Thank you.