When you are migrating from LastPass to 1Password. Shared vaults from LastPass will be imported as personal vaults in 1Password for those who are administrators of the vault in Lastpass. Other users will need access given back to them by the administrator importing the passwords. You can find information on sharing vaults in our article 1Password | Sharing and Managing Access to Vaults.
The most secure way to transfer your passwords is through the 1Password desktop app.