The Archwiki is telling you the proper or basic way to install an AUR package.
You should be familiar with this before using the AUR.
Pamac can handle this for you, but not as you typed it.
Its also possible that some package simply wont work well with an ‘aur helper’ and thus you may need to use makepkg for a successful install.
I again refer you to the wiki on the AUR. Please read it.
This is the command you are looking for, as mentioned by @cscs. You can also just use the graphical pamac interface and press the button to build. Pamac also looks for updates for aur packages you install.
The reason you should learn the normal process of installing aur packages is that AUR packages are not supported by the Manjaro team. Most packages will work most of the time, but when there is breakage, you are yourself responsible for the packages you have built. Understanding what happens behind the scenes will help you in the troubleshooting.
If there are errors or problems with this build operation, post the output here so we can help you. With this particular package it seems that the build might fail, because the package is flagged out of date and arch wiki mentions downloading files from the website. You may or may not need to do that part manually.
This product is not distributed by Paragon Software via AUR repositories. You can download the current version 9.7.0 for free from the product page. Please note that current version of Microsoft NTFS for Linux by Paragon Software Express supports Linux kernels up to 5.6. (Manjaro runs v. 5.8 currently)
At the same time, Microsoft NTFS for Linux by Paragon Software Professional supports Linux kernels up to 5.9 and includes additional features and utilities.
Most AUR packages dont come directly from the parent software company.
Why are you suggesting a manual install? If successful, that will simply create untracked files on your system leading to possible breakage or compatibility issues down the line.