Download !SEMTools
Before you download, make sure to check out the installation guide below.
How to install !SEMTools

Don’t open the file. Find it on your computer (usually in ‘Downloads’ folder)

{Optional} Copy the add-in file or move it to a folder on your computer where it won’t get lost or won’t be accidentally deleted, i.e. C://!addins/ folder

By default, Windows blocks files downloaded from the internet, and the !SEMTools tab may not appear in Excel if the file stays locked. So, you need to unblock the file by right-clicking it and opening its properties.
Connecting !SEMTools to your Excel

Open your Excel. Go to File -> Options -> Add-ins. Click the «Go…» button at the bottom

Find the file on your computer, double-click or select and click the OK button

The add-in should appear in the add-ins list with a checkbox marked. Press «ОК» to save your settings.
IMPORTANT: There’s no support for Excel for Mac, but you can install Windows and Excel on a Mac using a virtual machine (like Parallels).