Take the most recent DLL package you downloaded. Copy the .dll from that package and place it in the same folder with the EXE you're building. Do the same with the needed include .dba file. Then, on your project manager, link this .dba file to be included (as instructed in the ReadMe.txt file).
When you download a new version, the standard drill is to copy the new .dll file and include .dba file to the place where your EXE is being built.
That error happens when one of 3 things occur:
1) The DLL cannot be found in the location of your EXE at all.
2) The include file (NGCollision.dba) successfully loads the DLL but cannot locate all of the functions in the DLL (because you might have the wrong version of the DLL with your EXE)
3) You have the wrong version of the include file (NGCollision.dba) so it scans for the wrong functions in the DLL anyhow. This is similar to number 2 above.
Again, make sure you have the include file (NGCollision.dba) and the dll file (NGCollision.dll) in the folder with your EXE file and have them linked properly. And make sure these files are from the SAME package that you downloaded.