Issues updating High Sierra to Mojave
I want to update my (15 inch mid 2014) Macbook Pro from High Sierra to Mojave. I've followed this link
https://support.apple.com/en-us/HT211683
on safari, clicked the mojave link which takes me to the Mojave OS page in the app store. From there i have clicked "open" which would typically run the download or installer i assume.. but i just get a message saying "This copy of the Install macOS Mojave application is damaged, and can‘t be used to install macOS."
I've visited the link from a couple different sources in some question/answer threads and got the same thing. Any help would be appreciated. I'd rather run Mojave than anything later as i need it to download Microsoft office apps while still retaining optimal compatibility with audio production programs.
MacBook Pro 15″, macOS 10.13