This docker image is intended to be used on headless servers. Google Authentication is tricky. Please install gphotos-uploader-cli locally on your computer and follow the setup instructions. Make sure you use file authentification and provide a passphrase.
Then you can copy the created config folder to your remote machine and execute
docker run -d \
--name=gphotos \
-e GPHOTOS_CLI_TOKENSTORE_KEY=<PASSPHRASE>
-v <PATH_TO_CONFIG_DIR>:/config \
-v <PATH_TO_PHOTOS_LIBRARY>:/photos \
--restart unless-stopped \
zauberzeug/gphotos-uploader-service
Be sure to fill in <PASSPHRASE>, <PATH_TO_CONFIG_DIR> and <PATH_TO_PHOTOS_LIBRARY>.