sql error on script execution. try deleting repository before creating repository
It seems that the video tutorial missed a grant, the correct command is the following:

GRANT 
    CONNECT, 
    RESOURCE, 
    CREATE SESSION, 
    CREATE VIEW, 
    CREATE MATERIALIZED VIEW 
TO migration_repo 
IDENTIFIED BY migration_repo;


The database must also have the USERS tablespace.
I found the previous information in this thread.