After you've downloaded it, it goes in the plugins folder. You can find the folder in MuseScore Studio menu > Preferences... > Folders. Put it there, restart MuseScore, go to the plugins menu > Manage Plugins... and, if it's in the Disabled section, click on the icon, and click Enable. Restart MuseScore.
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You can get it here: https://musescore.org/en/project/tab-bold
After you've downloaded it, it goes in the plugins folder. You can find the folder in MuseScore Studio menu > Preferences... > Folders. Put it there, restart MuseScore, go to the plugins menu > Manage Plugins... and, if it's in the Disabled section, click on the icon, and click Enable. Restart MuseScore.