There are 3 types of password dialogs:
1. Password for a Personal folder (Only password)
2. Login for an Exchange server (User name, password, sometimes domain)
3. Login to a Windows folder (User name, password)
For the first two you can enter in the Easy2Sync task properties for both data storages the username / password. For the third dialog type you can enter username / password at the same place. However, if that dialog comes unexpected and you cannot answer it, please regard the respective paragraph in the "Problem solutions"