You can install MetaTrader 4 on a MacOS computer, and I have practical experience of installing it on BigSur. The only thing that for installation you need a minimum experience of understanding how MacOS works at the level of install/run the applications. The installation of the MetaTrader 4 application is described on the developer's website: Installation on Mac Os .
Download the .dmg image from the first link and install it on your computer. (Image URL: https://download.mql5.com/cdn/web/metaquotes.software.corp/mt4/MetaTrader4.dmg). After that, install the PlayOnMac utility and if it asks for updates required to start MT4, you must agree. I also installed Wine18 with PlayonMac for x86 in the process.
When all applications will be installed, MT4 should start in its standard configuration. Then you select File-> Open Data Folder and find there the \MQL4 folder into which you need to rewrite the indicators. I first unpacked them into my home unix directory, and from there I copied them through the x86on64 utility in MQL4 folder.
Video on how to do it from my partners: https://www.youtube.com/watch?v=peiaKzQbnPo
Also I successfully installed Indicators to MetaTrader via CrossOver: https://www.codeweavers.com/crossover. MetaTrader is installed using the core of CrossOver application and common full path to where you have copy indicators with Finder you can find using a button "open C: drive" in the properties of the installed MetaTrader in CrossOver. (virtual path is C:\Program Files\MetaTrader [4/5]\MQL[4/5] )
