There's several methods:
1. If you own the account the game has, and it's not banned, log into the account in question. Go to the old game. Download the latest version from that year in Configure Game/Place > Previous Versions.
2.If you do not own the map, You will need to find an older map collection with a compatible verison. p4ris made long ago, and esz made one too, but I also have an expansion that includes other maps as well.
3. If you have a map that refuses to open on 2013 and below, You will need to *convert* it. I suggest using the Beta Tool provided in the current 1.2 Snapshot, or to use the Finobe Wiki and use their method, text or video. Please do not do this for maps built for versions above 2014, because if you try to convert a 2019 game to work with 2011, the results are not going to be very pleasing.
If you're *sure* it's an older version, convert it with the guide on the Finobe Wiki, or use The Current 1.2 Snapshot's tool, even though it is unstable.