As he says, you don't install this as a mod. Just subscribe to get the folder of goodies. Once you open it, there are a TON of items you can use (if you have the right mods installed on your server) if you know what to do. I did not, but I taught myself.

The main question I see people asking is how to add one of these map items--so looking at the race track as an example, this is what I did to have it on my PingPerfect server--if you host your own or use a different host company, your steps may differ.

So first--open the Livonia_Trader_Events folder in the mod and then open the Trader Locations folder. Now open the Dolnik folder. Then, open the init.c file and scroll until you find the heading of Colosseum.

The init.c data look like this:
// COLOSSEUM

SpawnObject( "Land_Ship_Big_Castle", "9790.549805 237.199997 9049.330078", "22.999998 0.000000 2.000000" );
SpawnObject( "Land_Castle_Wall1_20_Turn", "9771.450195 230.313995 9083.980469", "-47.000000 0.000000 0.000000" );
SpawnObject( "Land_Ruin_Highway_Pillar1_Garage", "9749.240234 228.671005 9067.209961", "22.999998 0.000000 1.000000" );
SpawnObject( "Land_Castle_Wall1_Corner1", "9754.830078 230.220001 9048.910156", "25.000002 0.000000 0.000000" );
SpawnObject( "Land_Castle_Wall1_Corner1", "9766.490234 230.222000 9076.040039", "-67.000000 0.000000 0.000000" );
SpawnObject( "bldr_Monument_War2", "9750.240234 237.283005 9066.980469", "-67.000000 0.000000 0.000000" );

This is not json format so you can't use it as is (all of my map edits are done as jsons, not as additions to my init.c file.)
But, I found a QUICK way to convert c files to json. (not quick initially, but under 5 minutes now no matter the size of the map edit).
There is probably a quicker way to do this if you know coding language. I do NOT know coding. But I do know Excel and Google Sheets. So, I took the raw data from the Colosseum portion of the file and pasted it into Google Sheets. You will have to split the data as the XYZ and YPR are all in one cell initially, but this is easy to do if you know Sheets (I did this in a sheet I called 'sorting'). I added all the syntax needed in specific columns and then converted the spreadsheet to a json file. (There is a script you can run to do this).

The json data look like this when done:

{
"Objects": [{
"name": "Land_Ship_Big_Castle",
"pos": [9790.549805, 237.199997, 9049.330078],
"ypr": [22.999998, 0, 2]
},
{
"name": "Land_Castle_Wall1_20_Turn",
"pos": [9771.450195, 230.313995, 9083.980469],
"ypr": [-47, 0, 0]
},
{
"name": "Land_Ruin_Highway_Pillar1_Garage",
"pos": [9749.240234, 228.671005, 9067.209961],
"ypr": [22.999998, 0, 1]
},
{
"name": "Land_Castle_Wall1_Corner1",
"pos": [9754.830078, 230.220001, 9048.910156],
"ypr": [25.000002, 0, 0]
},
{
"name": "Land_Castle_Wall1_Corner1",
"pos": [9766.490234, 230.222, 9076.040039],
"ypr": [-67, 0, 0]
},
{
"name": "Nehr_Old_Soviet_Shop_Empty",
"pos": [9800.957031, 229.840012, 9082.257813],
"ypr": [-45, 0, 0]
},
{
"name": "bldr_Monument_War2",
"pos": [9750.240234, 237.283005, 9066.980469],
"ypr": [-67, 0, 0]
},

This would have taken forever to convert by hand. The spreadsheet and json export script worked PERFECTLY. You can do this to all the map items you want from the init.c files.

Once the json was saved (and validated), I uploaded the new Colosseum.json file to my mpmissions folder. Not done yet--just one more step.

In your mpmissions of folder, look for the cfggameplay.xml file, find the line that starts with "WorldsData" and then enter the name of the json for the racetrack in the array there.
"WorldsData":
{
"lightingConfig": 1,
"objectSpawnersArr": [
"Colosseum.json"
],

If you have more than one customized map edit as a json file, you would need a comma after the quotation marks of the Colosseum file and then add your next json on the next line. The last json file you list would NOT have a comma after it. (Always validate your json files before saving them to your server.)

If you have all the associated mods needed for the building items he used in creating it, you will have this amazing racetrack on your map. It is located in an empty field north of Borek. It is fun--but you may need to tweak slightly a few of the values of some items as they are not exactly flush with the ground. It still looks fantastic though. I keep the front gate blocked so people can't come in until we have an event.

If you want to see it in place, come check out my server: Recce-Hens PVE

if you know how to use Google and want my parent spreadsheet to convert c files to Sheets to Json, here is a link to the Google file: https://docs.google.com/spreadsheets/d/1_-rvGc6ZqOwFwviW06pYeOe-OZ3Yvcrb9wl8-HHAn2Q/edit. You need to make a copy to your own drive. I've left in the data for the colosseum for you to try to export.

I hope this helps at least one person be able to use things from OPs work.