WordPress Multisite blue print by Bitnami hosted on AWS Lightsail: Seeking help adding sites

Reference tutorial by AWS: https://docs.aws.amazon.com/en_us/lightsail/latest/userguide/amazon-lightsail-quick-start-guide-wordpress-multisite.html

I have launched a multisite WordPress instance on AWS Lightsail using WordPress Multisite blue print by Bitnami.

https://preview.redd.it/e50ew564c0od1.jpg?width=1024&format=pjpg&auto=webp&s=5fe8304a8aa0fce7d5ba7c93062f6a71e6f0180a

Facing hurdle adding sites.

https://preview.redd.it/d8igz798c0od1.png?width=1024&format=png&auto=webp&s=64adcc52d436855a4f0de252ab2a11822f07f411

In order to add domain MySite.com, it is needed to be pasted in Site URL field. But that field will not support dot(.). Must be missing something.