[Решено] Question on setting up my WPML

Background of the issue:
I am attempting to download and install the String Translations plugin for WPML on my site скрытая ссылка.

Symptoms:
I keep getting the error message 'Connection failed! Please refresh the page and try again. (Unable to register: Site key not matching)' when trying to install the plugin.

Questions:
What could be causing the 'Site key not matching' error during the installation of the String Translations plugin?
How can I resolve the connection failure issue to successfully install the String Translations plugin?