You can pause any active download from the MacWhat it does works is in App Store by right-clicking on the apps icon in the Dock and selecting “Pause” from the menu, you can Pause it there.
Resuming the download is just a matter of right-clicking again and selecting Unpause.
Since I have not used this for a whilejust downloaded Mojave, so doI can not know if it still worksverify your claim.
WhatHowever, it does works is inpossible that App Store, you can has disabled the Pause it therefunction in times with high demand, to allow for high bandwidth.