How to import multiple folders, avoiding crashing and mantaining links?

Hi, I have a problem with Unity. When I import a big pack of assets(trough pack of assets I mean multiple folders like material, flares, scenes, water etc) linked together (I copy all the folders of the pack inside Assets folder) , when Unity imports all, it crashes. If I import only parts of assets, all the links are broken. How to import all the folders without breaking the connections and how to fix crashing?

Go to Assets->Export Package and select everything you need from there. It may be a smart idea if you only need all the assets from the scenes you’re importing to just select the scenes and then check “Select Dependencies” Then export the package and import it in your new project

I made what I said and now Unity gives me the error: ‘‘Unable to join player connection multicast group.’’ I made a new asset pack, this time including all the files. I reimported it into a new project, and it gave me a crash, I think the same as importing the directories only. D:\Programs\Unity\Editor\Unity.exe, run by Administrator.
In the crash log, there was something like this: 68% memory in use.
2048 MB physical memory [646 MB free].
3943 MB paging file [2381 MB free].
2048 MB user address space [1035 MB free].

Do you think that RAM has something to do with the crash? If the ram is the cause, then what minimum capacity should I have to work?