Often there is need to get older version of plugins when with new update something breaks. Latest version of WooCommerce plugin 3.0.0 is best example, where hundreds of people left 1 stars reviews to WooCommerce plugin, cause update made their shop somehow nonfunctional. In that case best way, before next updates will fix bugs, is to switch back to old version that worked well.
How to do it?
First find your plugins page in WordPress repository, for WooCommerce it is https://wordpress.org/plugins/woocommerce/. Next you will have to find Advanced View link(see below screen shot).
On next page you have to scroll to bottom and there you will find option to download older versions of plugin.
Hope that this will ease your pain, when next crashing update will come to town!