By default new user is not visible on the map. You have to enable this option and set your basecamp manually. First create your "Slackline profile" by clicking on your user picture (see scree top right) then you can define your position (your basecamp) on the Members map. Your basecamp is your daily slackline location.
If your are still not visible on the members map then you have probably forgot to define your basecamp. Be sure that the option "My profile is public" is checked in your Slackline profile. If you are still not visible on the map then reset your location (pin it again, by clicking on the map).