Hello @mrsleitan, and welcome to the forum!
Did you download and install the bundle¹ that is in the folder the YouTube link sent you?
After installing the bundle, you simply had to do the following in Krita → open the menu ‘‘Settings’’ >> ‘‘Manage Resources…’’ in the opening dialog click on ‘‘Open Resource Folder’’, that will open a file manager dialog which will open in Krita’s resource folder (and if you dislike that way, alternatively this folder is also found when you enter %APPDATA%\krita\ in the Explorer address bar and hit enter), in the resource folder you simply had to copy the folder, you just unzipped and put falsely in Krita’s installation directory before, into the folder templates, which is meant to be a failsafe fallback to restore deleted resources.
If you had followed my little tutorial² on installing this, 
you won’t have this issue, but okay, I wrote it of course after @RamonM published his video.
But why on earth are you messing around in c:\Program Files\Krita x64)\share\krita\templates\? There is a very good reason that you should work only as a standard user under Windows (and every other OS), and that standard users are disallowed to enter any folder under c:\Program Files\ is for the same reason, they don’t have to be there and usually can only make things badder than they are.
Michelist
¹ A bundle is installed in Krita via the menu ‘‘Settings’’ >> ‘‘Manage Resource Libraries…’’ and in the opening dialog you have to click the button + Import in the next dialog browse to the downloaded bundle, select it and confirm the selection. Now Krita imports that bundle, and you can use its content, so the brushes in case of this bundle.
In case this BUNDLE comes in an archive-file, like ZIP or RAR for instance, then you have to unpack the archive to get the BUNDLE-File it contains, then you can proceed as described above.
² (this is an excerpt from another posting) By the way, if you are interested in more templates, @RamonM just published a pack of twelve new canvas templates named “Papers V1.0 - Classics” to get via Krita’s YouTube-Channel where he presents them in a new video. There you have to enlarge the video description with a click on more and follow the link below “DOWNLOAD: TEMPLATES :”, then you need to download at least the bundle and the ZIP-File.
To install the Papers V1.0 - Classics, you need to install the bundle → then unzip the archive → in Krita do Settings → Manage Resources... there click on Open Resource Folder → in the now opening dialog (a file manager window) copy or move the whole unzipped folder Papers V1.0 - Classics into the folder templates → restart Krita and find the templates in the new Group called Papers V1.0 - Classics. Happy painting!