Even if your school uses an automatic rostering integration, you can still sign in using your Google or Microsoft account. Magma Math matches accounts based on the email address connected to your profile.
If your Google or Microsoft email matches the email used through your rostering integration, it will connect to the same Magma account automatically.
This applies to integrations such as:
Clever
ClassLink
Canvas
Schoology
You can sign in using whichever login method is most convenient for you.