An error in Assistant when installing the Automation

The system exception is as below:
System.Exception: "NU1102: Unable to find package UiPath.Mail.Activities with version (= 1.12.1)


Looks like the package is not downloaded

Try to copy the package from dev machine as workaround or check if there are any firewall blocks to download the pckage and retry

For copying this the location C:\users\<Username>\.nuget\Packages

Same location in dev machine will have the pckage copy from there to the target machine