welcome to the notepad++ community, @Marcus-Östman
here is an easy guide how to install xml tools on your specific configuration:
(side note: as i can see in your report, you have a portable notepad++ 7.6.2, x64 in C:\Local Files\Notepad++\ and not in C:\Program Files\Notepad++.
this is good and makes it easier for you because all files will automatically go inside a sub folder of this same folder)
please get a new portable npp.7.6.2.bin.x64.zip from here,
extract npp.7.6.2.bin to your desktop,
copy the contents of npp.7.6.2.bin to C:\Local Files\Notepad++\ replacing your existing files.
then start notepad++.exe and open plugins admin as shown in this screenshot:
now enter xml in the search field and hit next until you see xml tools, select it as seen in this screenshot and hit install:
after the install you will have the full xml tools menu:
i hope this helps you.
additional note, if it is of interest: the correct plugin location for xml tools on your setup is: C:\Local Files\Notepad++\plugins\XMLTools\XMLTools.dll and C:\Local Files\Notepad++\plugins\XMLTools\libs\, so you can put them there manually, if you aren’t able to use plugins admin due to the same restrictions that prevent you from using the xml tools installer