Official Documentation

https://docs.microsoft.com/en-us/azure/active-directory/develop/quickstart-register-app

Its simple, Define App Name and Click Register.

Ask your Azure administrator to provide below delegated permissions for Microsoft Graph.

Configure authorized re-direct URLs:

// For [My Directory Groups Sync for Confluence Server & Datacenter], your Redirect URI will be:
<CONFLUENCE BASE URL>/plugins/ldapgroupsync/manage-ldapgroupsync.action

// For [My Directory Groups Sync for Jira Server & Datacenter], your Redirect URI will be:
<JIRA BASE URL>/secure/AdGroupSyncAction.jspa

// For [My Directory Groups Sync for Jira Cloud], your Redirect URI will be:
https://adgroupsync.ilaesolution.com/azure 

// For [Manage Inactive Users for Jira Server & Datacenter], your Redirect URI will be:
<JIRA BASE URL>/secure/DeactivateUserMainAction.jspa?oauthType=azure

// For [Manage Inactive Users for Confluence Server & Datacenter], your Redirect URI will be:
<JIRA BASE URL>/plugins/deactivateusers/manage.action?oauthType=azure

// For [Manage Inactive Users for Jira Cloud], your Redirect URI will be:
https://manageinactiveusers.ilaesolution.com/azure