Link with Signed Document

Hi All, we have 4 processes where we want to send the client the signed document by link.

The link would be send from Salesforce in a Salesforce email template.

The process was setup a few years ago, I can see that the link is being created - but the feedback is that the client cannot access the link. Most processes are like a repair on a house snagging, the agent makes the notes and on the spot let's the client sign. They value the message in the Salesforce email templates, so communication should be done through the email templates.

Any idea how I can troubleshoot here?