Hi, does anyone have a valid link to download oracle xe for mac? please help
There is no Oracle XE for Mac.
You can install e.g. virtual machine and there supported OS and XE database.
if you check out this blog, there wera a oracle database for mac, How to install Oracle Database 10g on Mac OS X Snow Leopard
If you read that blog post it says there is no official version.
You did ask valid download link for XE edition for Mac. There isn't one.
Of course with various hacks and doing unsupported stuff you could manage install something to any os.