Hi @simoncam. Welcome to GoDaddy Community! This is a shot in the dark, but I would guess that you're installing this on a Windows account. There could be a problem with the directory paths in the script since Windows uses \ instead of / sometimes when referencing file directories. Also, Windows accounts won't allow you to change permissions via FTP. Permissions have to be changed within your File Manager.
As for a solution, I'm not sure. If you are using Windows, you can try changing directory permissions in your File Manager. Other than that, maybe someone in the community will have additional suggestions. Hope you can figure this out.
JesseW - GoDaddy | Community Manager | 24/7 support available at x.co/247support | Remember to choose a solution and give kudos.