Alfresco Digital workspace Error when I ran npm start content-ee

[xavierjose]

I'm installing Alfresco digital workspace(ADW) and I ran the following command:

npm start content-ee

and I received the following error:
strict mode: "items" is 1-tuple, but minItems or maxItems/additionalItems are not specified or different
error: /home/etic/Desktop/Alfresco/app/.tmp/app.config.json: Unexpected token $ in JSON at position 399

And when I run npm start content-ee, the following line is added to my app.config.json file automatically inside "plugins": 

"folderRules": ${APP_CONFIG_PLUGIN_FOLDER_RULES} 

inside the object "plugins", That is, after executing the command, the plugins object looks like this: 

"plugins": {
"aosPlugin": true,
"contentService": true,
"folderRules": ${APP_CONFIG_PLUGIN_FOLDER_RULES},
}

As soon as I execute the command: npm start content-ee, my text editor is warning me that there is an error on the line where the following instruction is located: "folderRules":

${APP_CONFIG_PLUGIN_FOLDER_RULES}

and on the other the variable APP_CONFIG_PLUGIN_FOLDER_RULES
it doesn't exist in the .env file , simply when I run the command:

npm start content-ee

appears automatically.