Prerequisite
Your PBX must be set up for https before anything else. Salesforce requires use of an https address for callbacks.
See the instructions for https setup
You must setup the salesforce connected app prior to setting up the module
See the instructions for Salesforce configuration
The system needs to use https but the system does not need to be exposed to external inbound traffic. The redirect happens in the browser so your computer simply needs the ability to reach the PBX
Configuration
In the Admin UI click on the Settings menu and choose CRM Settings.
Assuming you have no other CRM configured you will see the following screen
For CRM Type choose Salesforce.
For PBX URL enter in the URL for your PBX. Note this must be a https address.
Click the Submit button.
On the reload you will get the Salesforce settings screen.
From the API setup above you should have copied down your key and secret for the app you created.
On the API Key field add the Key and in the API Secret field add the secret.
Click Submit.
Next, click the Get Salesforce Token.
This will open a new browser (tab or window) and will direct you to a Salesforce login page. If a Salesforce login page does not appear, check your browser settings/plugins to ensure nothing is preventing the new page from loading. If necessary use another browser or use Incognito mode for this step.
Login to Salesforce and click Accept. Follow whatever instructions are presented in order to grant the PBX access to your Salesforce account.
You will then be brought back to your PBX and see the following
if your User Count is 0 and you have just configured the system , from the command line of the pbx, run the following:
root@pbx ~]# fwconsole crm -u -f cache force updated prior to cache expiration
After that, if you click on the 
you should see something like this:
You can select which Zulu callpop type you want to use, just drag and drop what you want to use.
Also, you can choose to upload Recordings or Voicemails and associate them as attachments where appropriate then click Submit.
Finally, you must match your users from the PBX to Salesforce users.
Go to Admin > User Management > Edit the user you want to match, go to CRM tab and match your PBX user with your Salesforce user.
Additionally, if you use Zulu, you can choose to use "On Call Popup" option under your Inbound route or queues.
Go to Connectivity > Inbound Routes > Select your route > Zulu Tab
If you are using Zulu, then when you receive a call, a popup would be opened automatically pointing to the CRM or the chosen URL.