Register in Amazon Lightsail or sign in to existing account:
Go to Plesk Web Installer and select Install Automatically on a Cloud Serve
Get access and secret keys and specify them in Plesk Web Installer
Specify the region:
Select the instance plan
Download SSH key and upload it to Plesk Web Installer
Specify the instance name
Click Create Plesk instance button
Plesk installation begins and will take approximately 10-15 minutes. At the end of the installation one-time login link will appear: Copy the link and open it in the web browser to access Plesk.