C:\Program Files (x86)\Internet Download Manager\
If your IDM download panel isn't showing up, the easiest fix is to manually re-install the extension using the IDMGCExt.crx file. idmgcext.crx
Google Chrome forcibly disables "sideloaded" extensions that aren’t from the official store. Starting in 2021, Chrome began warning users about extensions installed via external .crx files. idmgcext.crx
Toggle the Developer mode switch in the top-right corner to On . idmgcext.crx
Understanding idmgcext.crx: The Core of IDM’s Browser Integration