I have an Admin account in PowerSIS. My administrator added me as a Teacher as I am now teaching a class, however I am unable to login. I have tried it with the password as well as with Google. With the password it says that my username or password is not recognized. With Google, it just shoots me back to the sign in page.
You can refer to the solution provided in this thread which discusses the similar issue you facing while trying to log in to your UC account. If you continue to face the same error you can also reach out to your district who can work with PowerSchool Support through a case and have them apply the known fix for login issues.