No. Shared mailboxes don’t have login credentials, so they are only accessible by licensed users who have been granted delegate access (full mailbox permission, send as, or send on behalf of).
Shared mailboxes do not include a personal archive or legal hold capabilities. If you need these features, then you can purchase either Exchange Online Plan 1 or Plan 2 and assign it to the shared mailbox.
There is no limit to the number of shared mailboxes though the size is limited to 50GB. If you require a shared mailbox that is larger than 50GB, an Exchange Online Plan 2 license will need to be assigned to it.