I am currently trying to install version 7.2.1 Dolphin. (This version because it's the last version that all my modules worked)

I have downloaded the Dolphin script, by cPanel into public_html directory.

When I initially start to install dolphin from URL, it immediately comes up with the mentioned error below. I have attempted numerous times to know avail. 

This page isn’t working

dyscoverme.net is currently unable to handle this request.

Can someone explain what is going on? I have followed install directions to the T.

Error 500 is a server error.  500 errors can be caused by php; I have seen it so that is why I mention it.  500 errors can also be hard to track down.

I am guessing you have modules that haven't been updated in the market.  Most modules compatible with Dolphin 7.3.5 will work with 7.4.x by changing the class constructor.

Make sure you have a lower version of php for Dolphin 7.2; if php 7 is set, Dolphin won't work and could cause the 500 error; see first paragraph above.

Ahh I see. SO you have found by adjusting Constructors, they work? Thats exactly the reason I was going to use the version that worked with the modules I purchased so long ago.

So if this is the case It should be safe to say I can use latest version of Dolphin?

 Yes, you have to use __construct for the class constructor and the parent as well.