Installing Plugins on Ubuntu

'm VERY new to Linux and am running Ubuntu 16.04.05 xenial in tandem with Chrome OS via crouton on my ASUS Chromebook. I have Audacity 2.1.2 (installed PPA - I think) up and running but need to get/install the Acx-check and RMS normalize plugins as they don’t come ready installed. It sounds like it should be simple, a straightforward command in Terminal and some moving of folders or something - I’m really not very competent, but having a Chromebook has necessitated diving in the deep end!
How do I do this? Do I use an apt get command and if so, what might it be, please very basic/step by step (lots of hand-holding required) to find and install these plugins? I’m still not too sure how terminal works and although I’m working on it, I need to get this set up ASAP so any and all help will be greatly appreciated.

Thanks,

Humble newbie

No, much simpler than that.
Both of the plug-ins that you mention are “Nyquist plug-ins”. Each plug-in is a single file with a “.ny” file extension.
Follow the “Per user installation” instructions for Nyquist plug-ins on Linux: https://manual.audacityteam.org/man/installing_effect_generator_and_analyzer_plug_ins_on_linux.html#nyquist_install

Thanks Steve, that’s all worked a treat. However after being unable to locate the rms-normalizer in the drop down plug-ins menu, I scoured other threads and realised it won’t work on Audacity 2.1.2. I have tried to update Audacity usuing th command “sudo add-apt-repository ppa:ubuntuhandbook1/audacity” but it keeps telling me “Audacity is already the newest version (2.1.2-1)” Any suggestions on this? Thanks, again!