Research and Engineering Studio instance Setup - AD users Sync to IDC. Unable to verify user email.

I am setting up a Research and Engineering Studio instance. I have followed the step mentioned in the document https://docs.aws.amazon.com/res/latest/ug/manage-users.html#sso-idc. I am able to sync my AD users to IDC Successfully. However on opening a user details, I can see a warning message saying - "Email not verifiedt Users must first verify their email address before they can begin to use certain features such as completing email-based two-step verification during sign-in."

However when I click on Send email verification link it fails with the error - "user pool is disabled"

What should i do to provide email verification for my users synced from AD?