I purchased two games today for my kids from GOG and one of them I was able to get to work on the device I downloaded it on, and transferred it to my Desktop and it also worked there as well. The problem I'm having is that the second game Roller Coaster Tycoon 2 Downloaded fine on my desktop but not on my desktop when I tried to copy the files to my desktop I keep getting an error message about the path not being there. Can anyone help with this?

Place all the downloaded files (the .exe and all the .bin files) in the same folder. Then open the .exe to install.

Yep,you can't really just copy to another pc (games files).Some games,you need to copy whole game untouched to new pc and then open setup to install.

Whether you can simply copy the files over to a different PC depends on the game. Some games do add a few extra stuff during installation, be those registry keys or files in the user folder that may not be copied over.
You have two choices, depending on how you installed the games in the first place. First choice is the one already mentioned, aka copy the installer to the new PC and run it. Second choice is if you used Galaxy, in which case you'll need to copy the files over (that you've already done), then import the copied folder to Galaxy and let Galaxy verify/repair the installation. This should add the missing files and/or entries.

Did you transfer the installed game, or the offline installer files? How did you download and install the said games on the first PC?

You must first realize there are basically two different ways to obtain (download and install) your purchased GOG games. You can even use both if you want.

1. Use the GOG Galaxy client. With this you can tell it to simply install the game from your online GOG account, in which case it downloads the needed files and installs the game for you. This is basically the same way you use a Steam or EA Origin client.

2. Download the offline installer (one or several files, depending on the size of the game) to your PC, and then run the installer yourself in order to install the game. You can download these offline installer files with various tools/clients, e.g. any web browser (Edge, Internet Explorer, Firefox, Chrome, whatever), or many third-party tools (gogrepo.py, lgogdownloader), or even GOG Galaxy has an option to download the separate installer files ("backup").

So if your intention is to install a game on several PCs in the household without having to download the game several times, then stick to option #2: download the offline installer files, copy the installer files to all the PCs, and then install it on all of them, one by one.

Copying the already installed games (either with Galaxy, or installed with the offline installer) to another PC might or might not work, depending on various factors. So you shouldn't really do it that way, if that is what you have done so far.

The safest way 2 ensure a game wld work on another desktop is 2 copy the offline installers then install it on the new desktop. I presume u hv just been copying the installed game folders which may or may not not work as some hv explained b4.