You need to be the HubSpot administrator to complete the Mapsly setup guide for HubSpot.
If you are not a HubSpot administrator before installing the Mapsly extension and creating a Mapsly trial account please enable 'Edit property settings' permission for each user that will be installing Mapsly.
You can access this permission in HubSpot by going to permissions > Account > Settings access > Edit property settings.