I've tried to install Minikube via Linux (Ubuntu 18.04) and have installed curl following these steps:

./configure --nghttp2 --prefix=/usr/local --with-ssl 
make 
sudo make install

My curl version is 7.63.0.

According to the Platform 9 guide, I wrote the following instruction:

curl -Lo minikube \ 
https://storage.googleapis.com/minikube/releases/v0.18.0/minikube-darwin- 
amd64 && chmod +x minikube && mv minikube /usr/local/bin/

This is the system's result:

curl (3) URL using bad/illegal format or missing URL

How can I fix this?