im using rathena 17165 (havent updated a some time )
you dont have to add or edit data or rdata grfs, actually it's not a good idea mess w/ those files, add the custom stuff to your grf or make a new grfs for dif contents instead.
all 3 files goes inside the data folder, together w/ sprite, texture, model, luafiles and other folders. Just drop it there, it may looks messy since you probably gonna have dif types of files like folders, desc tables.txt and things like that but thats ok, If you open one of the Gravity's grfs for curiosity you can see thats how they add maps too.
about the errors can, you post a pic of it?
some things that can cause errors (not always tho) is missing textures and models. If you downloaded a map that have extra files make sure to add it to the respective folders.
I downloaded a few maps that simply doesn't work, when i warp to it the client just crash and idk why ._.
one more thing, to rename maps you cant just right click and change the name of the file, to do it you must use a program like browedit or you will get errors.