Office, by hand

1 · Download and unzip

Right-click the zip → Extract All… You get manifest.prod.xml (Excel), manifest.word.prod.xml (Word) and INSTALL.txt, which repeats this guide.

2 Put the two files in a folder of their own

Create a folder — C:\Sumlion is a good choice — and move manifest.prod.xml and manifest.word.prod.xml into it. Not inside C:\Windows or Program Files: those need administrator rights to share. Office will read the files from here from now on, so don't delete the folder later.

3 Share the folder with yourself

Office only trusts add-in folders given as a network path (\\PC-NAME\Sumlion) — even when the folder is on this very machine. Sharing the folder is what creates that path:

1. Right-click the Sumlion folder → Properties → Sharing tab → Share…
2. In the dropdown pick your own user name (the one you sign in with) → Add → Share.
3. If Windows asks whether to turn on network discovery and file sharing for all public networks, choose “No, make the network I am connected to a private network”.
4. The last page says “Your folder is shared” and shows the network path under the folder name, like \\DESKTOP-ABC123\Sumlion. Select it and copy it — that is what step 4 needs.
5. Closed that page already? Right-click the folder → Properties → Sharing: the Network Path field shows the same path.

4 Tell Office to trust that folder

In Excel: File → Options → Trust Center → Trust Center Settings… → Trusted Add-in Catalogs. Paste the network path into Catalog URI, click Add catalog, tick Show in Menu, OK. Then close Excel completely and open it again.

5 Add Sumlion from the Shared Folder tab

Home → Add-ins (near the right end of the ribbon) → More Add-ins. The Office Add-ins window now has a SHARED FOLDER tab; open it, select Sumlion, click Add. Do the same once in Word.

6 Open the pane

Sumlion now appears in the Home → Add-ins panel and on the ribbon. Click it to open the pane, then sign in with your email.