Installation fails: "bin/grav: Permission denied"

I try to install Grav using Composer. It goes on until:

Generating autoload files
> bin/grav install
sh: 1:
bin/grav: Permission denied

Script bin/grav install handling the post-create-project-cmd event returned with error code 126

The user executing composer is in the www-data group that is used by both PHPMV and Ngnix.

Any idea?

Seems the bin/grav file is not executable. Check the permissions guide