Oracle - Extract user DDL for migration

I need to export and import data from a Oracle 9i to Oracle 12.2 database. This old app doesn't log in as one privileged user - it logs in for each user. I have hundreds of users with nothing but synonyms. I need to pre-create the users and their privileges so I can import. There are scripts all over the internet: * Ask Tom suggests import and an indexfile (which I find kludgy). * DBMS_METADATA.GET_DDL scripts, as well. However, being in a rush, I haven't found one script to cycle through all the users and generate their DDL and grants, etc. I want to run one 9i script to grab everything and one 12.2 script to create users, but can't find anything useful. Can you suggest how I should solve this? Or am I making this too complicated?