You might also find your answer in the LastPass Enterprise Manual.
How can I link my personal account to my Enterprise account?
The "Link Personal Account" is a tool for LastPass users who are part of an Enterprise system, but want to keep their already existent LastPass account separate. By linking their personal and Enterprise account, the user's personal account will appear as a shared folder in their Enterprise Account when they login to the Local Vault. You can learn more about the 'LInk Personal Account' tool at Link Personal Accounts.