I can't open my certificate with a double click
Once you finish the validation process of the SSL Certificate, you should receive the Certificate from the Certificate Authority either in a zip file or as a plain text. Depending on the type of the server mentioned during the Activation, the certificate is also issued in an appropriate format.
The next step will be installation of the Certificate on your server. In case the certificate should be pasted in a text format, you will need to open the Certificate with a default or an installed Text Editor on your machine. The Server Certificate will be the same as the common name you activated the certificate for (ex. yourdomain_tld.crt). You will need to right-click on it and ‘Open with’ any available Text Editor (Notepad, TextEdit, etc.), a double-click will only show the certificate information. The CA Certificate attached to the zip file should be installed as well to have the Certificate functioning properly.