If you already have a Mapsly account and would like to link it to your Salesforce organization, open your Mapsly tab in Salesforce, click Link existing Mapsly account (instead of Create new Mapsly account) and enter your Mapsly account login and password – this will link the two accounts via Single Sign-On:

Please note that you need to be the administrator of both Salesforce and Mapsly accounts to link your accounts with Single Sign-On.