After the installation , opening the software, you should see this window.
Open the Boards Manager in Tools -> Board: -> Board Manager.
Search “SAMD Arduino Boards (32-bit ARM Cortex M0 +) by Arduino” and click on Install.
During the installation…
When installation is complete, close the Board Manager and open Preferences in File -> Preferences.
Paste the URL:
in Additional Boards Manager URLs and press ok.
Then reopen the Board Manager in Tools -> Board: -> Board Manager.
On Type selects Contributed.
Search “Danyboard SAMD Boards by Giuseppe Caccavale” and click on Install.
Now you can select the Board: Danyboard M0 and proceed to the uploading of the first sketch.