Hi @CynthiaEdwards1,
As far as I know, the Canvas notification emails are not something that can be customized at all. Just wanted to put that statement out here for anyone who may encounter this thread at some point and would be curious about that.
For a solution in your case, I am thinking along the same lines at @adam_marshall. I did want to make one clarification to his post though. It is possible to set a password for the Canvas login (assuming you're not using SSO for these users at all) via the sis import process. The users.csv can have a password column that would work to set an initial password on their Canvas login.
Using the SIS process will mean no Canvas notification emails are sent out. You'd need to create and send your own emails, either manually or perhaps systematically via some kind of scripting language like Python. That should be doable, but sending a password via email is usually considered a no-no for security reasons these days. Is there a reason you don't want these students to set their own Canvas passwords (which would be the norm as far as I know for non-sso Canvas login accounts)?
-Chris