Not able to export (404 Error)

I’m editing a new website on a local host MAMP and I’m trying to export it as a File and it goes to a 100% and when I click Download Local Host, it gives me an error. 404 Not Found http://localhost:8888/Steel%20Fitness%20Club/wp-content/ai1wm-backups/localhost-steel%20fitness%20club-20190118-235221-172.wpress

HELP!