what is the impact of Migrating to Atlassian Accounts to our Viewer only users?

[Chris Walkup]

This may be a very basic question but it wasn't clear to me when reviewing the documentation...

do our viewer users (non-adims) need to create new Atlassian Accounts as well at our Admin users?  (in the migration process to Atlassian Accounts)

Until they create their new Atlassian Account (viewers, assuming they need to) will they still receive the notifications from any subscriptions they have already setup?

[atlassian-admin]

It isn't clear to me as well. I would like to know what I need to communicate to our viewer users about the migration. What will they experience? Will Atlassian blast an email to all of our users explaining the changes and what to do next? As an admin, I don't feel well equipped with enough information about the change. We need to know what kind of information our users will receive once we finish the migration steps/prompts.