Does the following thread help?
Also does the following help?
https://picard.musicbrainz.org/docs/basics/
Section:
"Matching files & saving
The tracks in the right-hand pane will start out with a musical note icon, and as the tracks become associated with your files the icons will change to one of the following:
a small rectangle ranging from red to green indicates the quality of the match, where red is a bad match and green is a good match
a red error triangle means Picard encountered an error (e.g. permission error), click the file and read the status bar in the bottom of the Picard window to see the error
a green check mark indicates the track is up to date and saved
You can drag whole directories, multiple files or album clusters onto albums and Picard will attempt to match the dragged files to the album. Any track that doesn’t match up well enough, will be added to an “Unmatched Files” sub-folder specific to that album. You can drag files out of this folder and into the right slots in the album to fix up the files that Picard couldn’t get right. "
Do the track times and track names match with your files?