If you did not explicitly install Dashlane then my take is that you should do everything in your power to purge every trace of it from your system. Consider that the program/add-on/plug-in is there to collect passwords and login information and store them somewhere (where?). Can you see any downside to giving something you don't know anything about this information? Like f'rinstance if it collected your banking and credit card information for later use?
I did a bit of searching for information about this program. This bit might be of interest:
"Should I remove dashlane?
The internet security community strongly recommends that you remove Dashlane if you find it installed on your machine or attached to your internet browser as a browser add-on or extension and use reputable Antivirus or Anti-Malware software to eradicate any existing malicious files.Aug 22, 2015"