You can now get Office Add-ins from the Store or use Add-ins you already have from right within recent versions of Word for Mac and Excel for Mac.
If you're looking for a built-in add-in such as Solver or Analysis ToolPak, select the Tools menu and then select Add-ins.
Get an Office Store add-in for Word or Excel for Mac
On the Insert menu, select Add-ins.
To get new add-ins, select Store. To use add-ins you already have, select My Add-ins.
The add-ins you'll see will depend on the app you're using and the kind of Office 365 subscription you have.
Office for Mac doesn't currently support organization-based add-ins.
Get a VBA add-in for Word or Excel for Mac
On the Tools menu, select Add-Ins.
In the Add-Ins available box, select the add-in you want, and then click OK.
Office Add-ins aren't available in Office for Mac 2011. They're only available in newer versions.