I have looked in the faq and in the wiki. I can not find any information on how and were to install plugins.
I want to install tiny MCE but do not know where to put the folder.
When you installed or upgraded to V5 and following the install you would have been presented with a list of storage locations. That will show you where the install them.
admin > wp integration > storage locations
I just found this thread when also looking for a guide on how to install tinymce… I saw the list of storage locations when first clicking on the forum but I never would have assumed that the page had insinuated where to install plugins.
Finding this type of solution via ‘search’ is exactly why you guys have these forums 🙂
its obvious to us, but of course we coded it! 
we will probably try to add the info directly on to the plugins and themes panel too for those that dont search around…