Customers who do not want/cannot manage an "account"

We have set up some processes that require users to set up an account in order to make their application. The reason for this is that there is some necessary back and forth between the service team and the applicant (read and electronically sign docs etc)

Some users cannot or will not set up an online account. As such they are managed outside of liberty entirely. Ideally the service team would like all applications to go through the system so they all exist in one place.

Has anyone come up against this and how did you process applications through the system without the customer signing in to an account? Thanks.