Problems with shared Numbers file

Hi there,

I have problems with accessing a numbers file that a collaborator has sent me. When I click on the file link (shared via email), I am being sent to my icloud account (where I am logged in) and then receive the following message:

This spreadsheet is unavailable.

The owner stopped sharing, or you do not have permission to open this spreadsheet.

My collaborator has confirmed that the file has been shared with me and that I have permission to view it.

Is there anything else I could try (beyond logging in and out, which I have done several times)?

I would hugely appreciate your help. Normally I do not use Numbers but for this work it is crucial I do.

Thanks in advance,

M