In most cases the answer is no. No password information was migrated from OMRS to OPUS. Each member was prompted to create a password when they received the OPUS welcome email.
Usernames also differ in most cases. In OMRS, your username was the email address you had on file as your main email. The email that was primary in OMRS served as the basis for your OPUS username, but also included an extension of .kkytbs (email@email.com.kkytbs).