The behavior you described, where the database file locks for the first user and prevents subsequent users from accessing it, is likely due to file locking mechanisms.
When a user opens a file, it can acquire an exclusive lock (write lock) on the file. Other users trying to access the same file may be blocked until the lock is released. This behavior is common in file systems, including Azure file shares.
Azure file shares block unencrypted connections for security reasons. Ensure that you’re connecting from a client that supports SMB encryption (e.g., Windows 8/Windows Server 2012 or later). Connect from a virtual machine (VM) in the same datacenter as the Azure storage account to benefit from an encrypted communication channel. Verify that the “Secure transfer required” setting is disabled on the storage account if your client doesn’t support SMB encryption.