1. Download "Manifest"
2. Create a folder and put manifest.xml into that folder.
3. Right click on folder > Properties > Sharing > Network Path.
4. Click "Share" and then copy the /path/ to the folder.
5. Open Excel > Options > Trust Center > Trust Center Settings > Trusted Add-in Catalogs.
6. Paste the /path/ onto "Catalog Url:" and press Add Catalog.
7. Press the check box.
8. Restart Excel
9. Home > Addins > More Addins > Shared Folder.
10. Add Ketcher. It will be on the Addins section where NCATS is.