Pro Tools supports Avid and RTAS format plugins and doesn’t support stand alone VST Plugins.
With this said,
there are quite a number of ways in which you can use VST Plugins in Pro
tools and will discuss that here.
Because VSTs will not work directly in Pro Tools because it is an unsupported
plugin format.
The following methods can be used to host VST Plugins in Pro Tools:
1. Blue Cat Audio Patchwork.
2. NI Maschine
3. Reaper
4. Vienna VEP 5
5. Nugen Audio Sigmod
6. Plogue Bidule
7. DDMF Metaplugin
Blue Cat Audio Patchwork

This is essentially a patch bay for plugins that allows the user to create a
number of plugin chains in an easy to use manner,
Blue Cat allows you to makes it reliably easy to compare plugin chains in parallel.
Furthermore,
Patchwork works as a great host for both VST instrument and effect plugins,
it can also host AU plugins.
All you have you to is basically just purchase Patchwork, install it on your
system.
then open up protools and look for it and then you’ll able to load your VST
plugins with it pretty much easily.
NI Maschine
Maschine is another great tool that can help you load up your VST plugins
into protools.
It is essentially a well crafted complete production studio.
Maschine is able to host AU and VST Plugins relatively easy.
Be warned though that this is one much more pricey options for VST
hosting in pro tools.
if you already own it then you’re pretty much good to go.
It will work for Pro Tools 10 and below.
Reaper

The process of hosting VST Plugins in Reaper is bit different compared to the
other two options discussed so far.
With Reaper, you’ll be able to host your VST through ReWire.
Reaper is a great tool and it is one of the great options that you can use
when looking to host VST.
It is advisable to install Reaper before installing pro tools if you wish to use it
for the purpose of using the rewire function.
Once rewired from pro tools you can easily select Reaper from the insert
selection for it to load up so you can run your VST through it.
Vienna VEP

Vienna ensemble pro supports it’s own sample players including those of
third party VST/AU plugins.
It has become one of the best cross platform network solutions in audio production.
The hosting and mixing application of Vienna allows you to have a network of
both Mac and PC without the need for extra audio interfaces or midi.
This plugin is another great way to have your VST plugins hosted within Pro
Tools.
Nugen Audio

The Nugen Audio Sigmod plugin utility is an all around great utility for Pro Tools.
This is one of those tools that you need in order to have that missing
functionality within your Digital Audio Workstation.
You’ll enjoy enhanced functionality with Nugen and it will allow you multiple applications,
including a dual mono option available for independent processing of two
parallel channels.
Plogue Bidue

Bidue is another way to host VST plugins in pro tools first.
Pro Tools first does support ReWire and this is a great plus because it means
you can run other DAWs that support ReWire.
Bidule is a great cross platform tool that is great for Plugin hosting,
therefore, it may be a great option for hosting your VSTs in Pro Tools First.
DDMF Metaplugin

The Metaplugin 4 can be a great option for plugin hosting within Pro Tools and quite a cheaper one too.
it costs about 49 bucks.
Conclusion
It doesn’t matter which folder you put your VST Plugins in because Pro Tools
doesn’t allow the VST format for plugins.
But you can use a variety of VST hosting plugins within Pro Tools that allow
you to load VSTs within Pro Tools and the location of your VST Plugins can be
anything that works for you.
Related Pro Tools Articles
How Long Does It Take To Master Pro Tools?
Is Pro Tools The Best DAW For Mixing?
Sources
My plugins do not show up in Pro Tools – Sweetwater
How to add plugins in pro tools (and 5 places to find them) – Ever Cast
How to Install VST Plugins in Pro Tools – Syntheway
Easy Ways to Load Plugins in Pro Tools – wikiHow