Error on upload: "Impossible to create the root directory..."

In Craft 3.2.10, I’m getting this error message when I try to upload an image asset:

Upload failed. The error message was: “Impossible to create the root
directory “/Users/me/Work/Client/repo/web/craftcms-assets/project-slide-photos”. mkdir():
Permission denied”

I’ve made the permissions for project-slide-photos to 777 and 774, and likewise tried both for the parent directory. Is it trying to create a directory that’s already there? I tried removing project-slide-photos also, and it still doesn’t work.

What do I need to do to make my assets upload into this directory?

Edit: Wondering if using Docker Compose could have something to do with this:

docker-compose.yml:

version: '3'
services:
    web:
        image: 'flipbox/php:72-apache'
        ports:
            - '80:80'
            - '443:443'

        volumes:
            - '.:/var/www/html/'
        environment:
            ENVIRONMENT: dev
            DB_SERVER: db
            DB_USER: craft
            DB_PASSWORD: craft
            DB_DATABASE: craft
            XDEBUG_ON: "yes"
            XDEBUG_HOST: "host.docker.internal"
            XDEBUG_IDEKEY: "PHPSTORM"
            APACHE_DOCUMENT_ROOT: "/var/www/html/web"
    db:
        image: 'mysql:5.7'
        restart: always
        ports:
            - '3306:3306'

        volumes:
            # Location to import a database dump. 
            - ./src:/docker-entrypoint-initdb.d
            # Location of the generated mysql files.
            - ./mysql:/var/lib/mysql

        environment:
            MYSQL_ROOT_PASSWORD: password
            MYSQL_DATABASE: craft
            MYSQL_USER: craft
            MYSQL_PASSWORD: craft