How do I save an Excel Add-in (XLAM) file?

Hellocmccarro​, 

You can still save Excel add-ins in newer versions of Excel, but the option only appears under Save As, not Save.

To save a workbook as an add-in (.xlam), open the workbook that contains your VBA macros, go to File → Save As, in the Save as type dropdown select Excel Add-In (*.xlam), choose a location (by default Excel stores add-ins in C:\Users<YourName>\AppData\Roaming\Microsoft\AddIns), and click Save.

To load the add-in, go to File → Options → Add-ins, at the bottom select Excel Add-ins from the Manage dropdown and click Go, then browse to your .xlam file and check the box to enable it.

If you don’t see .xlam in the list, make sure your workbook contains VBA code, since Excel won’t offer the add-in format for a plain workbook. 

If macros are blocked, check File → Options → Trust Center → Trust Center Settings → Macro Settings and allow macros with notification.

Microsoft documentation:

https://support.microsoft.com/en-us/office/add-or-remove-add-ins-in-excel-0af570c4-5cf3-4fa9-9b88-403625a0b460