Every map has a title and a slug. They sit together in the thin row at the very top of the editor, and the slug is what turns into the map's public web address.
Where to set them
At the top of the editor you'll see two fields side by side. The left one is the Map title. The right one is a box that reads yourteam.map.au/ followed by the slug field, with an › arrow that opens the live public map in a new tab.
The title
Type a clear name in the Map title field, for example Riverside Shopping Centre. This is the name shown to visitors and in your list of maps, so make it something you and they will recognise at a glance.
The slug (your link)
The slug is the short, lower-case last part of the address. If your team address is yourteam.map.au and you set the slug to festival, your map lives at yourteam.map.au/festival. Keep it short, use hyphens instead of spaces, and stick to letters and numbers.
Related settings
The part before the slash (your team address) is set for the whole team, not per map. To change it, or to point your own domain at your maps, see Change your company name & web address and Custom domains & your web address. To decide what shows at your bare address with no map in the link, see Choose what your web address shows.