Open Utilities > Plugin Manager and select export3DM to enable the plugin. The plugin will be listed under Autodesk App Store. Please select export3DM_2017 ( Alias 2017 or Alias 2016) or export3DM_2018 for Alias 2018 or export3DM_2021_3 for Alias 2021.3
Select the Auto Load option to automatically load the plugin the next time Alias starts.
The plugin will be installed under File > Export menu, as Export 3DM

Click on Export 3DM either to save the contents of the current stage or active objects to a 3dm file.
Open Export 3DM Option box, to select either All objects or Active objects.
The following datasets are translated

The installer that ran when you downloaded this app/plug-in from Autodesk App Store will start installing the app/plug-in. OR, simply double-click the downloaded installer to install the app/plugin.

You can unload the plugin without uninstalling it by unchecking the "Load/Unload" check box associated with the plugin in the Autodesk® Alias® Plug-in Manager. You may have to restart Alias to completely unload the application.

Please ensure the following pre-requisites are met. 
.NET framework 4.6.1 or above. Download the framework from https://www.microsoft.com/en-us/download/details.aspx?id=49981 
Microsoft Visual C++ 2019 Redistributable or above. Download the files from https://aka.ms/vs/16/release/vc_redist.x64.exe

To uninstall this plug-in, exit the Autodesk product if you are currently running it, simply rerun the installer, and select the "Uninstall" button. OR, you can uninstall it from 'Control Panel/Programs and Features' (Windows 7/8.1/10), just as you would uninstall any other application from your system.

LicenseManger will automatically pop up when the plugin is invoked for the first time. A trial subscription for 10 days can be activated by clicking on the "Trial Subscription" button. Click on the "Buy Subscription" button for a one year subscription. The cost of a subscription is USD 99. Internet Connection is required to enable trial subscription and to activate regular subscriptions. After buying the subscription, click on "Activate Subscription" to activate your subscription. The License Manager will automatically pop up 9 days before the end of the subscription period.

Limitation: The default layer in Alias is called DefaultLayer and cannot be deleted or renamed.

• Work Around: The translator will rename the layer to "_Default_" so that round trip transfers don't end up with multiple layers called "DefaultLayer".

Limitation: Some trimmed periodic/closed surfaces may not get trimmed properly.

• Work Around: Please detach such surfaces into two before the transfer or convert them to shells, using SurfaceEdit->Stitch function.

Limitation: Some complex multi-level instances might not transfer properly.

• Work Around: Please use Edit->Expand Instances to create real geometry before the transfer