Mojave installer in the AppStore says it's damaged and can't be used

I need to update to the Mojave OS from Sierra (I can't use Catalina or Big Sur due to the need for some old 32 bit apps in my work)

I found a thread about this, and also a page on the support site. But when I get to Mojave in the App store and click to open it I get this message: This copy of the Install macOS Mojave.app application is damaged, and can‘t be used to install macOS.

Note that I saw this reported as far back as April 2020. Will Apple fix this? What are folks who can't use Catalina and Big Sur supposed to do?

I followed the instructions on this page: https://support.apple.com/en-us/HT211683

And followed this link: https://apps.apple.com/us/app/macos-mojave/id1398502828?ls=1&mt=12

I've looked for other possible links, but haven't found anything.

I am unable to get critical applications for my work unless I upgrade to Mojave or later. Please, help!