How to change QuickSight VPC connection setting by Active Directory admin user?

Hi, I try to use QuickSight with Active Directory. QuickSight should have VPC connection setting to connect with Redshift inside VPC, so I tried to configure but I couldn't do it in a weird way.

https://ap-northeast-1.quicksight.aws.amazon.com/sn/admin#vpc-connections After push the add button, It showed an AWS login screen. Then login with a root account, backing to the setting screen, it refreshed a few times. I just tried to input the setting but they were vanished. After a few seconds, the screen changed to an error page, which said "Invalid account".

I think AD admin user doesn't have permission to change VPC settings, so I was required to login with an authorized account. But the screen doesn't look to work normally in this case?

How should I set the setting in this condition? Please help.

Thank you,