'An unexpected error occurred…' message when selecting Themes

Hi there,

I’m new to WordPress – (graphic design background) and have installed the latest version of WP locally on my Macbook. Using MAMP which is running without issue. Least I think it is – the two status lights are green.

However, once I using themes options under the ‘Install Theme’ tab, I am getting the following error message on a new page:

An unexpected error occurred. Something may be wrong with www.ads-software.com or this server’s configuration. If you continue to have problems, please try the support forums.

The site is local with address:
/*https://localhost:8888*/

Have looked on the forum, but not finding any solution that is helping…

Hope someone can help and direct me in the right direction.

Many thanks!