In Veeam ONE, the remaining capacity of each backup repository server can be viewed under the Data Protection View. This section provides detailed information about the storage utilization and remaining capacity of backup repositories, allowing administrators to effectively monitor and manage storage resources.References:Veeam ONE User Guide, Veeam ONE Data Protection View Documentation

Veeam Agents are designed to provide backup solutions for physical and cloud environments. They support various operating systems, including Ubuntu (a Linux-based OS) and Windows Server. These agents ensure that data on servers running these operating systems can be effectively backed up and restored. However, Veeam Agents do not support FreeBSD, IBM iSeries, or iOS as these platforms require different backup solutions or are not typically used in environments where Veeam operates.References:
* Veeam Agents User Guide
* Veeam Help Center: Supported Environments

Explanation
https://helpcenter.veeam.com/docs/one/deployment/connect_servers.html?ver=120

The "Migrate" option is typically used when you're moving the entire Veeam Backup & Replication infrastructure, including its configuration and database, to a new server environment. This option ensures that the configuration settings, jobs, and other relevant data are transferred accurately to the new servers while maintaining continuity and ensuring minimal downtime for backup and replication operations.