Generally, the MapInXL tab automatically appears in Microsoft®™ Excel®™ when you open it.
If this tab does not appear, go to the Excel®™ main menu, then to Excel®™ Options. Choose the "Add-in" menu and go to "Manage" > "Disabled items", then "Reach".
Tick in the box in front of MapInXL Addin, and click on "Activate".
The MapInXL tab will appear at the next start of Excel.