Did not think you can download vs2019 anymore.
however, you need/want/should/good idea to install the .net framework tools for using and designs for a .net framework "desktop" application.
I don't think they are installed by default.
So, from vs2019, use tools->get tools and features. The installer/setup page will launch. You can close the topmost page, and then you want to select these options:
(I'm using 2022 for this, but 2019 should be the same).
So, choose this:
And then choose to add/install these things:
scroll down a bit, make sure these are also selected:
Once done, exit VS, and re-launch. You should now have the .net framework bits and parts.