Hi @angelmarfo, thanks for reaching out to us.
I would recommend trying to install the key while your other plugins are disabled and your theme is set to a default such as Twenty Twenty-Two. This would rule in/out a Javascript conflict between Wordfence and another plugin preventing the scripts on this page from working correctly. A check of your browser console might show red errors which you can also paste/show us here.
If you have no luck with that, could you use a service such as Snipboard to send us a screenshot or paste here the exact error message you’re seeing? The stage of the problem occurring could be of assistance as your domain doesn’t seem like it should be affected by anything else.
Thanks,
Peter.
