Click-lock Alternative?
There is a built-in equivalent for trackpads, called dragging, which you find in System Preferences > Accessibility > Trackpad Options:



In case this is not sufficient for you or you need to use a mouse, have a look at the answers to this question. Currently the following third-party apps are being mentioned: 


Hammerspoon (free) is a popular choice for gestures and automation. It offers a feature called "Grab Scroll".
Karabiner (free) a similar and popular tool.
Smooze (commercial)
Smart Scroll (commercial)


Better Touch Tool (commercial) is my personal favourite as it allows so much more, such as another Windows-inspired feature, called window snapping, etc. The procedure here would be as follows:


Open BTT preferences
Select Input device, i.e. Mouse
Select Trigger. The one you mention (i.e. long press) currently seems not to be available. (I suggest you make a feature request on their forum. The developer is usually very open to such requests.) Instead you could do e.g. middle-click.
Select action. Go to Window Resize &amp; Move > Start/Stop Moving or search.