uploading theme to google cloud for wordpress (click to deploy) - ERROR

New to google cloud and after many hours of study I really thought I could so this

I'm used to cPanel, have plenty of exp with ftp and set up the sftp successfully with google cloud BUT ...

Errors all the way with attempting to transfer the theme

Can't find any upload limit in wp-config and followed a tutorial to increase file size permissions using terminal (mac) which also appeared successful

Now STUCK

Please Help if you can. I need step by step as I'm a total noob

Example of the error: (Error: /var/www/html/wp-content/themes/pressive/thrive-dashboard/inc/notification-manager/includes/admin/views/backbone/summaries/items/actions/wordpress-notification.phtml: open for write: no such file or directory)

I understand about editing file writing permissions BUT also can't find a tutorial that successful helps me to do that. It's Click To Deploy and most tuts are for Bitnami (which I avoided as the advice was that's too hard! lol)