Hi there firts make sure everything is fine and correct in your project.
-Build light and save all
-rigt click on your project in content browser and fix redirectors
-save all
close unreal engine
-go to your project file
delete intermadiate and saved folders
delete collections and developers in the content folder.
-zip whole project with is name
-upload it to cloud drive(google drive etc)
-on the publısh tab in marketplace page paste the link in place, write its name as 4.24-4.25 etc…
project version is the engine version you made it with.for example if you made your project in 4.25 than your project version is 4.25 but generally people use lower versions so I advice you make your project in 4.24 it will mostly support both 4.24 and 4.25 and future versions.
very dirty but that is whole procces.