i have tried 3 times to install Monterey on my MacBook air and it will not install it is a compatible model.

Try booting in Safe Mode and then deleted any existing installer (in Applications folder) and redownload and try again.

How to use safe mode on your Mac - Apple Support

Make sure you have enough free space before doing this.

What exactly happens when you try?

You need about 40gb of free disk space.

Try booting in Safe Mode and then deleted any existing installer (in Applications folder) and redownload and try again.

How to use safe mode on your Mac - Apple Support

According to Apple…

"If upgrading from macOS Sierra or later, your Mac needs 26GB of available storage to upgrade. If upgrading from an earlier release, your Mac needs up to 44GB of available storage."

From: How to upgrade to macOS Monterey - Apple Support

There are chances the AV Software, thought disabled, is still active and possibility the root cause of your issue.

Suggestion would be to remove it before attempting the Big Sur installation as Per Developers Specific Instructions.

Besides, there are no Windows-like Viruses that affect macOS. So the protection is really zero for a non existing issue plus money down the rabbit hole with Zero Return.

Is there and Anti Virus software installed that may be interfering with the process ?