Before starting the installation process, please make sure you’ve created your CSR and also received your SSL Certificate files from the trusted Certificate authorities-
Once you’ve done these both task, let’s jump on the installation process –
Login to the Plesk Control Panel.
Select the Websites & Domains tab and click on the domain you need to install an SSL certificate for.
Choose the Secure Your Sites option
Select the SSL certificate that was created while generating the CSR code.
Find the Upload Certificate Files section
Click Browse and locate the certificate and the CA bundle files from your computer. The certificate file should have .crt extension, the Bundle one can be .crt or .ca-bundle.
After both files are chosen, click Send Files.
Otherwise, you can copy and paste the certificate along with the CA bundle into the corresponding boxes under Upload the certificate as text and click on Send Text.
Go back to the Websites & Domains menu and click on Hosting Settings next to the domain name you want to secure.
Locate the Security section on the next page, select the certificate you want to apply from the drop-down menu and make sure the checkbox SSL Support is checked.
Click the OK button at the bottom of the page. The certificate is now installed and applied for the website.