To add a profile on Postgrain, it is necessary to inform the username and password that is used to log into Instagram.
Postgrain uses a mobile device to perform profile actions. When we request a username and password, it means that you are logging in mobile so that we can access the data and display it on Postgrain.
As this is a new device (which you never logged in to), Instagram may request a security check via "It Was Me"/Email/SMS, through the information already linked to the profile, and must be accepted on a device already logged in or through Instagram Web.
It is worth mentioning that it is extremely important to have a valid email and cell phone number linked to the profile, as Instagram may request security verification by them.