Hey there!
I had the same problem. Well, I’m new at using wordpress, PHP and making sites. So, I don’t know if what I did was the best way of solving it, but it worked!
I just installed the plugin manually. Then, I could activate it.
I’ll tell you how I did it just in case:
Download the plugin file. Then, access your PHP server and follow this way:
Wp-Content >> Plugins
Find the Easy Contact Form plugin in your local computer and transfer it to the “Plugins” folder in the server. After you did, access the WordPress administartion panel and activate it.
That’s what I did. Hope it works for you, too!
Hugs!