The created user should be assigned to a group so that permissions are assigned automatically otherwise, just for testing, you may assign the permissions on the user manually and test.
The error you pasted is Oauth error which means its not configured correctly. You'd definitely need to check the configurations again or may be do it from scratch. This configuration must work in to proceed further & creation of user.
Could you validate Twitter's client Id/secret are configured correctly? Does the created user/group have appropriate permissions?
Create Users If checked, logging in with a Twitter account will create an AEM user entry and add them as a member to the selected user group(s). Default is checked (strongly recommended).
Groups: (Recommended) One or more member groups to which created users are added. OOB Twitter login module would create user with in AEM who needs to be added to a group with appropriate permissions.
User Path Location in the repository where user data is stored. For a community site, to ensure permissions for members to view one another's profile, the path should be the default /home/users/community.