Problem: The client wants to translate their Contact Form 7 but cannot find the option to install the necessary plugin. Solution: We recommend downloading the Contact Form 7 Multilingual plugin from here. After downloading, navigate to your site's backend, go to Plugins > Add New > Upload, then upload the zip file you downloaded, and install and activate the plugin add-on. Next, follow the step-by-step guide on using Contact Form 7 with WPML.
If this solution doesn't look relevant, please open a new support ticket in the WPML support forum.