It appears you have copied this with an XML-like structure. You can maybe adapt it to SmileBASIC by erasing the first part of it, up to where it says "<MML>", and then encompassing the entirety of the MML with "".
Your MML string needs to be in a labeled DATA block that ends with DATA 0. For example:
@SONGDATA
DATA "mml string here"
DATA 0
Then you have to use BGMSETD to load it to a BGM track. Such as:
BGMSETD 128,@SONGDATA
Not sure if this will help, but here is an MML example I made for a game over track.
Note: All of the "DATA"s can be condensed into one by making it one huge, continuous string, except the last one.
