I cannot install new macOS Monterey
When i try to install the new macOS Monterey, the download doesn't start, I don't know why.
MacBook Air 13″, macOS 10.14
The Age of this computer will Govern what newer version of macOS it will Qualify to install.
Use About this Mac from the Apple Icon on Desktop - the required Information will be there.
Does this computer appear as Listed and qualifying for an upGrade to a newer version of macOS ?
Computer Qualify for the Monterey upgrade
With the above information in-hand - follow this How to get old versions of macOS and verify what version this computer Qualifies to install.
Safari will open a redirect and open the Apple Store where the download can commence.
If Yes, suggest having at least 50 GB of Empty Space on the drive.
It will allow the Full Version ( about 12.xx GB ) to download, then expand and then commence to install.
If there is Third Party Security Software installed - remove it.
It will interfere with both the download and installation process.
Always make a Time Machine Backup before doing any upDates / upGrades