Let me start by saying that you guys are going awesome work on Freepbx. It is highly appreciated. Now moving on to my issue, I just upgraded to 10.13.66-18 to test out the Zulu UC (v. 13.0.50.16). I tried to install the UC plugin for outlook following the Zulu Office 2016 Plugin but was unsuccessful. I could not perform the second step since “Manage Add ins” button was missing on my Outlook 2016. After searching online, I came across this article according to which, “The Store is for web-based add-ins. These need an Exchange back-end in order to function. POP3 and IMAP accounts are not supported for these type of add-ins.” To test this out, I made a hotmail account and added it to my Outlook 2016. Eureka! The store button appeared on the ribbon and I was able to install the Zulu UC plugin. However, it seems that I can only use Zulu UC with my Hotmail account and as soon as I click on my other pop3/imap accounts, the Zulu icon disappears. 
Can we just have a simple .dll or .exe for the plugin. Or is there a way around this?
No. Outlook 2016 and higher no longer support those plugins. It’s Web based or nothing.
Really? Zulu, something clearly business-oriented, can’t be used with an IMAP account?
So, without the outlook integrations, the only thing that remains is a softphone … that I can replace with any (free) voip phone?
I don’t believe…
What do you mean a IMAP account? Zulu is more then a softphone. It does Click to Dial, Call Pop Ups, Faxing, Chatting and contacts from your PBX
Sure! But @ravenkane wrote “However, it seems that I can only use Zulu UC with my Hotmail account and as soon as I click on my other pop3/imap accounts, the Zulu icon disappears”, so, I don’t understand WHY che plugin depends on the kind of account (hotmail/outlook365 Vs POP3/IMAP)… 
OK now I understand what you are asking. We have no control over this. Talk with MS. They designed the Add On system for 2016 not us and we are at the mercy of them and what they allow.
I would also like to use the Zulu Communicator add-in inside a standalone instance of Outlook 2016 that is not tied to an Exchange account, and ran into the same problems as described above. However, other add-in developers seem to have gotten around this MS-imposed limitation for add-ins. I have add-ins from gSyncit (calendar, contact sync) and PDFArchitect that were installed locally without dependency on MS 365 cloud or having an Exchange account. Anyway for a software engineer to figure out how they did it?
Feel free to open a feature request at issues.freepbx.org under Zulu but right now our focus is on the new 3.0 client we are trying to get out this year.