A boardview (component placement) file (board DAY16EMB8B0). Shared as “day16emb8b0-b-bella-tp.brd” — a .brd file, 29.4 MB.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @ShareMan_Electronic_Files. Enginerys does not host this file.
How to open a .brd file
The most common boardview extension. Several unrelated formats share it, which is why one viewer opens a .brd and another refuses it.
OpenBoardViewFlexBVBoardViewerAllegro Free Physical Viewer (Allegro .brd only)