I'm confused with this part: "DB Instance scrubdin contains MyISAM tables that have not been migrated to InnoDB." So you have the mixed Maria and InnoDB content in your UNA database?
I am not sure (my knowledge on this is very limited), but I copied the error as it appeared. Any suggestion on DB type we should use with UNA?
It doesn't relate to UNA directly - you should use only 1 engine in the DB: InnoDB or MariaDB but not together.