Hi @steffanie,
Welcome to the Auth0 Community!
I understand that you would like to assign Roles to users using a Post-Login Action.
First, I would like to clarify that Auth0 Actions will work for any application type (e.x SPA, RWA, M2M).
Meaning that you can assign roles to a Regular Web App.
Next, I recommend going over our How can I use the Management API in Actions? FAQ which includes a working code snippet for assigning roles to users.
Please let me know if you encounter any issues getting this to work. I’d be happy to help!
Thanks.