iCloud Drive on a Mac - How to config one or more folders to be always available.

I pay for 2 Tb of iCloud storage, that help me manage the extremely low space I have on my MacBook Pro (yes, I know terrible decision, I will upgrade next time I change it). But for now, I use Optimaze Storage. here is my problem. I once a wile work on a project, and I need ALL the files inside one specific folder to be on the computer. I can't download every time the files. I know that if I use the "Cloud download" button on the finder, the computer starts to download them all. But, the system, clears the space if I don't use it in a while.

Can some one help me?