The OpenVPN agent component that is reporting a problem is the component that makes it possible for OpenVPN Connect v3 to run unprivileged (not requiring admin rights). There are certain actions that require admin privileges like opening the TUN/TAP adapter and setting up routing. The agent service takes care of that. Apparently though that agent is unable to do its job.
Given your problem description, the most likely cause of the problem is a failure to install the TUN/TAP adapter, therefore when the agent is requested to open a TUN/TAP adapter, there isn't one, and the request fails, and therefore everything simply does not work.
I believe the root cause of the problem is related to a problem installing the driver on Windows 7. First of all I should point out that Windows 7 is no longer supported by Microsoft. But we also know that OpenVPN Connect v3 will work fine on Windows 7. But one issue that we know about is that if you don't have Windows 7 updated to the latest still available updates, then you will not have the required update that adds support for checking code signing done with SHA256 type certificates. And that is required if you want the driver installation to proceed correctly. This update could be obtained separately.
More information on this can be found here:
https://support.microsoft.com/en-us/top ... a4cde8e64f
I believe that, just likes in our test setup with Windows 7, if you have the correct update installed that adds support for SHA256 code signing, then you should be able to install the driver correctly.
And finally, some antivirus software might hold back the driver installation. So it's possible that the problem can be resolved by temporarily disabling antivirus for the installation process to succeed.