Themes/Branding is setup within the front of QuicklySign. This is the process to retrieve the name and keys for the created branding.
Watch a walkthrough on how to achieve this here Using custom branding VIA the API

Get Themes

This is used to return list of theme names and theme keys. The theme key can be used to specify which theme to display for a given document. NOTE that the below requests require an access_token set under the HEADER.

GET /themes/
This returns a list of default themes.

Key - Unique key for the theme/brand, this can be used when specifying which brand to use when creating documents using the /document_packs/ API.
name - The specified name associated with the particular theme/brand in question.

{
    "data": {
        "themes": [
            {
                "key": "ahFzfnRoZW1hc3NpdmUtbGl2ZXIhCxIUQWNjb3VudEJyYW5kaW5nVGhlbWUYgICgmvzmtwsMogEHc2FuZGJveA",
                "name": "Branding example theme"
            },
            {
                "key": "ahFzfnRoZW1hc3NpdmUtbGl2ZXISCxIFVGhlbWUiB3NhbmRib3gMogEHc2FuZGJveA",
                "name": "sandbox"
            }
        ]
    },
    "status": {
        "status_code": 200
    }
}

If a team_key is specified, the list will also include "branding themes" that you've created in the UI.
The next step will explain the team_key retrieval process.

GET /themes?team_key=<team_key>
This returns a list of themes for the specified team key provided.

{
    "data": {
        "themes": [
            {
                "key": "ahFzfnRoZW1hc3NpdmUtbGl2ZXIhCxIUQWNjb3VudEJyYW5kaW5nVGhlbWUYgICghqXDzAoMogEHc2FuZGJveA",
                "name": "API theme example"
            },
            {
                "key": "ahFzfnRoZW1hc3NpdmUtbGl2ZXISCxIFVGhlbWUiB3NhbmRib3gMogEHc2FuZGJveA",
                "name": "sandbox"
            }
        ]
    },
    "status": {
        "status_code": 200
    }
}