The mod automatically sets up dll files needed for screen reader functionality and removes them after the game is closed. If the mod is working correctly, you will hear the current version of Say the Spire read out by either your screen reader or SAPI if your screen reader is not running when the game launches.
The mod narrates UI elements automatically. It will also announce many game events as they occur without any additional player input required. To access additional statistics and tooltips however you will need to use the buffer system.
there is an extra set of controller and keyboard inputs to provide information. This is generally refered to as the buffer system and is mapped to the right stick or control plus the arrow keys on keyboard by default. As you move over various UI Elements, contextual buffers will appear. These are just lists of various pieces of information about the element you're focusing on. For example, if you hover over a card, the card buffer will be automatically focused and will contain information such as the card's name, energy cost, description, etc.
Think of buffers as a way to refer to different areas of the screen quickly, similarly to how you could scan visually. For example, while hovered over a card, you can move to the player buffer to view player info without having to move there with the other controls. Buffers are also used to provide access to UI Tooltips (for example character information on the character selection screen, etc).
The buffer system is also used for the map. Using the buffer controls lets you browse available paths and choices when available. For more information, see the map section.