Install module Simple OAuth (OAuth2) in drupal 8

1- Download and install module Simple OAuth (OAuth2)
I use this version in my example: https://ftp.drupal.org/files/projects/simple_oauth-8.x-4.5.zip

2-The same for requires modules Consumers (Version: 8.x-1.11)

3- Enable modules Simple OAuth and Consumers in admin/modules

4-Configure the simple_oauth module by navigate admin/config/people/simple_oauth click on the Generate keys button after the popup opened there is a field named Directory for the keys then I put the current directory path of my web application using php functiongetcwd ( ) then click Generate then the field public key and private key is filled then I click on Save Configuration

5-Add Consumer or Client

5-I start to add a Client by add on the top of the page on the button Add Client (admin/config/services/consumer/add)
5.1 then a message appear to me to add new role I create new Role I create a role named Consumer
5.2 I return to the page Add client (admin/config/services/consumer/add) I add in the field label label_simple_oauth then I add in the New Secret field I enter client_secret_simple_oauth then check all the checkboxes Is Confidential and Is this consumer 3rd party? and Click Save and That it
6- Test it in postman (available with google extension)

Method:post
Body format: form-data
Body keys:
grant_type: password
client_id: UUID of the consumer (select it from the list of Consumers admin/config/services/consumer the column UUID) you can use the one you add it.
client_secret: client_secret_simple_oauth (located in the field New Secret of consumert)
username: username of user in the web app
password: password of user in the web app