Thanks for the video. I have a couple of questions so that I am better able to understand your problem.
It would also help to know which Mac operating system and version of Kontakt you are using.
1. You have 2 folders in the Finale Music Templates location. The folder that you open the file from, is that one you created yourself or did you copy the templates package to that location?
The Music Templates folder should only have the template files stored there. The MIDI Device XML Files should be in a different location. The same is true for the Percussion Library folder.
2. In the video, after opening/creating a new file from the templates you load the VDL Percussion library. Is there a specific reason for this step?
That library is already a part of the templates from The Write Score. Are you wanting to use them in a Finale file that you created that is not from the template package?
3. The video does indicate that SnareLine Manual Layout is part of the template file. Have you tried assigning the Percussion MIDI Map first then setting the layout?
The Percussion MIDI Map may assigned in the Score Manager > far right column (Perc MIDI Maps). If the SnareLine Manual is not in that list then
you would need to copy it back to the MIDI Device Annotation folder.
That folder is found in two (2) places.They are:
Macintosh HD > Library > Application Support > MakeMusic > Finale (or whatever version you're using name) > MIDI Device Annotation
Macintosh HD > Users > Library > Application Support > MakeMusic > Finale (or whatever version you're using name) > MIDI Device Annotation
I always copy the XML files to both locations.
Make sure you copy the VDL255 Battery.xml file. This contains all of the Battery instrument maps. The only way you could have deleted the SnareLine Manual MIDI Map was to have opened the file in a text editor and deleted just that section of code. Since you indicated that you were sent another copy of the templates that Battery.xml file should not have been altered.
Mac OS 10.12, 10.14, 10.15, Win7, Win10
VDL2.5.5, Finale 2010-14.5, Finale 25-27
Kontakt 4-6, various other soft synths