Operating an account to view all signed contracts

I am currently preparing to implement Adobe Sign.

With Adobe Sign, it is my understanding that there are two ways to view a signed contract
1. Log in with the sender's account and check it.
2. Log in with the administrator's account and search with the sender's account.

I would like to prepare an account to review all signed contracts, but I don't think it's optimal for 2. above, as I may not know the sender's account.

However, if you think about it in 1. I think you need to unify the sender address with one address.

How do you think this will be the most common case to manage in actual operation?