If I understand correctly, your requirement is a transactional report showing login records between a date range.

I didn't quite follow if it should also display either the latest user details associated with the records within that time frame, or each login record displays the user details at that time.

Either way SSAS does not tend to be great for transactional reports. It is designed for analytics, like if you wanted to show number of logins during a period, average time logged in per month, number of failed login attempts, etc.

However, making your user table a slowly changing dimension (SCD type 2) does seem to architecturally make sense to meet the requirement.

This would simply mean adding a surrogate key to your user table (that becomes the new primary key) and effective from and to dates. Then login attempts are associated with the user record at the time instead.

I would look into dimensional modeling and ETL tools that help you maintain a slowly changing dimension.