Thank you for reaching out. Unfortunately, older versions of SQL Server Migration Assistant (SSMA) such as 8.0 or 7.x are not available through the public Microsoft Download Center. Only the latest versions (e.g., 9.5, 10.3) are officially listed.
If you require a legacy version due to compatibility needs, the best course of action is to open a support ticket with Microsoft. The support team may be able to provide access to archived installers or offer guidance tailored to your environment.
You can start a support request here: https://support.serviceshub.microsoft.com/supportforbusiness/create
Thanks,
Akhil.