just installed trial version of Negative Lab Pro and trial version of Adobe Photoshop Lightroom 6.5 and i don’t see Negative Lab Pro in my applications on my mac. and there is not an option in File > plugin in Lightroom, any help?
my OS is Big Sur 11.7.10
Negative Lab Pro is a plugin for Lightroom Classic (LrC), not a standalone application. You will find it in the Plugin Manager of Adobe LrC.
The latest version of Lightroom Classic is 14, perhaps you have installed Lightroom instead, latest version 8.
so basically i need Lightroom Classic (LrC) to make it work
the thing is i can’t install LrC, because my iOS is too old apparently 
What OS are you running?
Lightroom Classic is an application for computers with Windows or macOS. The requirements can be found here: Guide | Negative Lab Pro
Okay. You’re running macOS. But you installed Lightroom (cloud), not Lightroom Classic. Both versions are available on the photography plan.
If your Mac isn’t supported by a recent version of macOS then you’re indeed stuck with an older version of Lightroom.
There is however a thriving community of enthusiasts who work hard to make recent versions of macOS run on older unsupported machines. You may want to check openCore Legacy Installer from Dortania. It’s entirely at your own risk though. I bit the bullet and installed a recent macOS version on my MacBook Pro from early 2015 in order to install the latest version of Lightroom Classic… works like a charm!
Okay but I have tiff ready to edit. How do I pull up NLP in LrC??
Can this be used in regular Lightroom?
In regular lightroom Classic. It comes with your subscription. The icon has LrC on it.
that was the first thing i wrote 
iOS is Big Sur 11.7.10
which is apparently too old. my mac is from late 2013
If you want to keep your Mac, you can check if OpenCore Legacy Patcher works for your hardware:
https://dortania.github.io/OpenCore-Legacy-Patcher/MODELS.html
You might be able to find an installer for Lightroom Classic version 10, which is the version you need for macOS Big Sur. Newer versions of LrC might work too.
https://helpx.adobe.com/ie/lightroom-classic/kb/macos-big-sur-compatibility.html