Authentication failed for Elasticsearch and Kibana

I have download Kibana from git clone directory according to the instructions mentioned in a question on elastic.co like this:
git clone https://github.com/[YOUR_USERNAME]/kibana.git kibana
cd kibana
git fetch origin
git checkout v7.10.2
I have installed nvm and node and npm and yarn. Basically I want to generate a plugin and I have succeeded in it. but when I start kibana to test the plugin it gives me authentication error on browser side.
yarn kbn bootstrap
node scripts/generate_plugin my_plugin_name
and I have generated a plugin
when I write command
yarn es snapshot --oss" and
yarn start --oss
It gives me authentication error even kibana version is on basic version like 7.10.2
node version is 10.23.1
npm version is 6.14.10
yarn version is 1.22.19
so need your help guys to get out in this issue.