NEW MAC BOOK AIR user - Help Installing Mac OS Catalina

[sate]

Hi!

My sister has a mac book air (mid 2013) and her bf restarted it before giving to her. Now, since it's unsupported, we can't log into the App Store. We aren't very familiar with Mac OS, we've been using Windows ever since. I have read that I can install Mac OS Catalina to this mac book. To be honest I have no idea about how to do it.
these are the things i have done so far:

1. Download the Catalina Patcher
2. I have done it and downloaded Mac Os Catalina which is 8gb
3. After it was done downloading, it has three options (Install the OS - Create Bootable OS - Make ISO something) - Install the OS was not clickable.
4. Now i don't know what to do next.

If anyone, someone, could help that would be really great.

 

[Lifeisabeach]

Whoa whoa whoa! Stop right there... no patchers. No ISOs. Let's step back a bit here. You say it was "restarted" before being given to her? Or restored? What, exactly, happens when you start the Mac up?

That model may be unsupported, but you absolutely can still use and log in to the App Store. You just need an Apple ID.

Is there a specific need to install Catalina? That MBA will run the latest version of macOS, Big Sur. Unless you have a need for Catalina, I would go straight to Big Sur.