should create custom AUTH_USER_MODEL after making a custom user model

I followed this to create a Costume user model.
Before, I was have a field added_by = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE) in a model for books store thta have title and review and added_by field. Now, after I created a costume user the apps start having trubble with using settings.AUTH_USER_MODEL should I use somthing els. Also, I deleted my migrations after I created the CostumUser model, but I'm still having the same error that says column myApp_BooksModel.added_by_id does not exist

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