As a server operator with access to the admin commands or the console, type in the command /ver. This will display a rather cryptic text, but you only have to filter out to information as seen in the following picture:

The text aligned in red represents the name of the software you use for your server. Make sure it’s saying either Spigot. Others might work as well, but if you want to be on the safe side, you might want to switch one of them.
Their wiki pages: Spigot
The text inside the orange rectangle displays the Minecraft version of your software. Make sure it’s at least 1.7 If it’s something lower than 1.7 then you must update it to at least server version. Older versions are known to be incompatible with some plugins and contain a rather large amount of bugs, so it’s generally a good idea to update.

It is very likely that you’re already running a supported version. But if you want to verify it you must open a terminal on the machine on which your server is running on. If it’s a Windows machine click on the Windows symbol and search for bat, cmd or powershell (Win10+ only). Otherwise, if it’s a Linux machine open your terminal. It is possible that you need a software, such as PuTTY, WinSCP or Bitvise, to connect to your distant machine.
If you’re inside the console type java --version to display your currently used version. If it’s printing that the command is missing then your machine isn’t even viable to run the Minecraft server. Otherwise, it should print something like this:

It should print either Java 8, Otherwise, you’ll have to update it to at least version java version.

Dependencies

1. Download the zip file.
2. Open the zip file.
3. Extract the zip folder SquidGames and put in the folder /
4. Restart your server.
5. You can now play on the map.

Installation with schematic