Installation failes…

Dear all,

On my site, Alfie Weather fails to install.
Using WP, the “waiting for…” remains there it seems forever.
Using FTP will bring up the message “are your sure” and after accepting returns to the installed plugins.

Suggestions are welcome; I could not find anything here (sorry for that) but I am sure that I have overlooked something.

Thank you in advance, Jan.

https://wordpress.org/plugins/alfie-wp-weather/