Hi, you need the vmf files first, you probably already know that.
You should be able to open them without problems but you should keep several things in mind:
-You must replace models and textures
- In larger maps you will have to optimize them again because beta optimization does not work well in retail, this does not always happen.
-A lot of npcs and entities will be obsolete, you will have to replace them.
Doing the things above is very important because sometimes due to anything stupid on the map, the map doesn't work properly, you can always port the assets.
I have fixed the map d1_canals_02 and it was not working because of a stupid model.
That would be it, thanks for reading.