A normal user is authoritatively denied the following api.
(The following are errors from postman)
“Message”: “Access Denied”,
“data” : 
I really want to do the following.
Get display group information available to the general user from api.
Is there any good way?
I dont think this possible. There are quite a lot of calls in xibo, which can only made by a root user.
EDIT: I think you could assign these displays to the normal user or give the normal user permission to that display. In the CMS you can set permissions per display
That is right - you need to give your normal user permission to the
displaygroup pages for these calls to work.
Permissions via the API are the same as via the web UI.