i'm gonna assume that each one of those things are one mod each and probably a kind of zip file. you better try to unzip them with 7zip or some other extractor. I think the mod folder is in them with it's text.mod document.
anyway take one of those ugc_1181575896 etc and try extract it inside the mod folder (C:/Users/your username/Documents/Paradox Interactive/Stellaris/mod),. If it has a folder named "something" with a "something.mod" document you are good.
now we assume the "something.mod" is called "Murder AI.mod"
open it with a text file editor like notepad/notepad++ and you'll see something like this.
name="Murder AI"
path="C:/Users/your username/Documents/Paradox Interactive/Stellaris/mod/Murder AI" (this needs to be edited with your folder path)
tags={
"AI" etc
}
picture="thumbnail.png"
supported_version="2.5.*" (note if this isn't 2.5.* it means it wasn't updated for last stellaris version. you gotta change to 2.5.* for it activate in-game)
remote_file_id="ugc_1181575896"
note some mods contents are in zipped form after extraction from archives like those ugc_1181575896
and path needs to written like this
archive="C:/Users/your user/Documents/Paradox Interactive/Stellaris/mod/pdx_13/downscaled_ships.zip"
also in the actual mod folder(as in Murder AI folder) where the mod contents really are should have a doc as well called "descriptor.mod" and it should have the same contents as the other doc. if it's in zipped form it's in the zip.
The path and "supported_version="2.5.*" need to be edited in this "descriptor.mod" as well just to be on safe side.
Note if the mod is made for an older version and it has issues you can use winmerge doc comparer program to update it yourself if you feel like it.
These things are explained more here too:
https://stellaris.paradoxwikis.com/Modding
here's how they should look so the current launcher detects them more or less:
