What the people you send to see
Signing
Somebody you send to does not need an account and is never asked to make one. They open the link, read what they are being asked to sign, and sign once.
The link
It is long and random and carries no name — not yours, not your client's, and not the request's. Anyone holding it can open the request it belongs to, which is why it is sent to one address and why it should not be forwarded.
Signing
A signer sets their signature up once for the whole request and it applies to everything they were asked to sign. They are shown the consent statement before they sign, and it names every document it covers.
If a link does not work
A link answers differently depending on what is wrong: that it is not valid, that the request has ended, that it is not this person's turn yet, or that they have already signed. It never says which firm or which client the request belongs to.