To install a free SSL certificate from Let's Encrypt in Plesk Control Panel, follow these steps:

Step 1: Log in to your Plesk Control Panel.

Step 2: Go to the Websites & Domains tab.

Step 3: Select the domain/subdomain for which you want to install the SSL certificate.

Step 4: In the domain/subdomain settings page, scroll down to the Security section and click on the SSL/TLS Certificates option.

Step 5: Click on the Add SSL/TLS Certificate button.

Step 6: Choose the Let's Encrypt certificate option.

Step 7: Specify the certificate details: Enter a name for the certificate to identify it within Plesk. Select the checkboxes for the domain and any additional domains/subdomains you want to secure with the certificate.

Step 8: Configure additional certificate settings (optional): You can choose to include or exclude the www subdomain by selecting the corresponding checkbox. Specify the email address where Let's Encrypt can send important notifications related to the certificate.

Step 9: Click on the Get it free button to initiate the Let's Encrypt certificate installation process.

Step 10: Plesk will communicate with Let's Encrypt to generate and install the SSL certificate automatically.

After the installation, you can test the SSL certificate by accessing your website using https:// in the URL instead of http://. Check if the SSL padlock icon appears in the browser's address bar and if the website loads securely.

That's it! You have successfully installed a free SSL certificate from Let's Encrypt in Plesk Control Panel. The Let's Encrypt certificate will be automatically renewed by Plesk before it expires, ensuring continuous secure access to your website.