What is ViaMia and why do I need it?
Your keyboard is powered by QMK, an open-source framework to aid in the development of custom and semi-custom mechanical keyboards. QMK has a companion program called VIA which is not open source. VIA uses a repository of definition files to enable the program to speak to keyboards like your Portico75. Recently, new definition files have not been approved anywhere near as quickly as they have been in the past.
To work around this issue, a developer known as tkon99 created a patch program that modifies your VIA installation to point at a repository he maintains on GitHub, so that keyboards can continue to be added to VIA. While this is not an ideal situation, it is a reasonable workaround until such time as the VIA project begins approving and adding definition files again.
You may have noticed that when you open VIA with your new Portico75 connected, it isn't recognized. While TKC has submitted the necessary files to the VIA project to enable support for the Portico75, they have not been approved yet.
How do I make it work?
At https://viamia.github.io/, click on Just Get Me Started, unless you want to read more about the project.
Click the appropriate download button for the type of Operating System you use.
Run the program once the download is complete. You may receive a Safe Screen error on Windows, you will have to click More Info then Run Anyway to proceed.
The program will detect your VIA installation and ask if you want to proceed. Answer Y, then press Enter. The patch program takes a while to work, even on new PCs.
Upon completion, you can open your VIA installation again and it should connect to your new keyboard.