Hi @acaselli,
Welcome to the Auth0 Community!
Finding the correct format of the import can take some trial and error.
Do you have access to the params listed here?
I would suggest creating a dev/test user and trying to import their password successfully. For example, create a user with a password of password and try to import that to Auth0 and log in with those values.
You may also want to search for related info about the algo you are using. For example, here is a thread that could be insightful.
Let me know if you have any questions.