not able to login to app store but able to login to i cloud

See if you can upgrade to 10.11, 10.12, 10.13, 10.14, or 10.15, see sys requirements...

How to download and install macOS - Apple Support

https://itunes.apple.com/app/os-x-el-capitan/id1147835434?ls=1&mt=12

http://updates-http.cdn-apple.com/2019/cert/061-41424-20191024-218af9ec-cf50-4516-9011-228c78eda3d2/InstallMacOSX.dmg

but you can edit the domain part of the URL and change the "/cert/" to "/macos/" to still be able to download it:

https://updates.cdn-apple.com/2019/macos/061-41424-20191024-218af9ec-cf50-4516-9011-228c78eda3d2/InstallMacOSX.dmg

macOS Sierra - Technical Specifications

https://itunes.apple.com/us/app/macos-sierra/id1127487414?ls=1&mt=12

Fix for 10.12 createinstallmedia "not a v… - Apple Community

Fix for 10.12 createinstallmedia "not a v… - Apple Community

macOS High Sierra - Technical Specifications

General Requirements

• OS X 10.8 or later
• 2GB of memory
• 14.3GB of available storage to perform upgrade*
• Some features require an Apple ID; terms apply.
• Some features require a compatible Internet service provider; fees may apply.

Mac Hardware Requirements

For details about your Mac model, click the Apple icon at the top left of your screen, choose About This Mac. These Mac models are compatible with macOS High Sierra:

• MacBook (Late 2009 or newer)
• MacBook Pro (Mid 2010 or newer)
• MacBook Air (Late 2010 or newer)
• Mac mini (Mid 2010 or newer)
• iMac (Late 2009 or newer)
• Mac Pro (Mid 2010 or newer)

macOS High Sierra - Technical Specifications

https://itunes.apple.com/app/macos-high-sierra/id1246284741?mt=12

macOS Mojave 10.14.6 - Technical Specifications

General Requirements

OS X 10.8 or later

2GB of memory

12.5GB of available storage (OS X El Capitan 10.11.5 or later)*

Some features require an Apple ID; terms apply.

Some features require a compatible Internet service provider; fees may apply.

Mac Hardware Requirements

For details about your Mac model, click the Apple icon at the top left of your screen and choose About This Mac. These Mac models are compatible with macOS Mojave:

MacBook (Early 2015 or newer)

MacBook Air (Mid 2012 or newer)

MacBook Pro (Mid 2012 or newer)

Mac mini (Late 2012 or newer)

iMac (Late 2012 or newer)

iMac Pro (2017)

Mac Pro (Late 2013; Mid 2010 and Mid 2012 models with recommended Metal-capable graphics cards)

Don't use FireFox for these links…

https://itunes.apple.com/us/app/macos-mojave/id1398502828?mt=12

macOS Mojave - Technical Specifications

https://itunes.apple.com/us/app/macos-mojave/id1398502828?mt=12