Can’t add Bunifu to Toolbox

I followed this guide and do the right steps

https://docs.bunifuframework.com/en/articles/3707185-how-to-install-and-activate-bunifu-ui-or-bunifu-dataviz-via-nuget

But when i’m about to add dlls, i’m getting an error “there are no components in that can be placed on the toolbox”

What to do??