Not able to install OS macbook

As you have just re installed an operating system the mac will have been working very hard and therefore will be running hot. It will also be indexing which uses a lot of energy, so it give it time to settle down.

Make sure the mac is well ventilated and any ventilation holes in the body are not covered up or full of dust.

The picture you shared shows your mac is trying to install macOS Sierra, not High Sierra.

If your MacBook was running High Sierra previously then the drive would probably be running the

APFS file system format that Apple introduced with High Sierra.

macOS Sierra can only run HFS+ file system and the disk needs to be formatted as Mac OS Extended (Journaled).

You need to reformat the drive in your mac.

Restart your mac to your Recovery HD, hold down the Command and R keys while restarting.

The mac will boot to Recovery, select Disk Utility.

Click View in the menubar, select Show All Devices.

Now highlight the Disk in the left panel, not any of the indented Volumes,

so it will be the top level disk icon you choose.

Click on Erase.

Give the Disk a unique name.

Format: Mac OS Extended (Journaled)

Scheme GUID Partition Map.

Click Erase.

When that is done quit Disk Utility, then select Reinstall OS.

Click Continue.

Hopefully this makes a difference.

If you have other devices that share the same internet connection do not use them while the

mac is downloading. As you are using a MacBook you are probably using WiFi to connect to your

router, WiFi is not as stable as a cabled connection, so the less demand on your internet connection the better.

Interesting your picture says Macintosh HD - Data, which would indicate that your mac was running macOS Catalina,

can you confirm that to be true or not.

I have no idea about iPads, visit the iPad forum, Using iPad - Apple Community

Yes leave it alone, see how it goes, don't interfere.

See you chose the 'unique' name of Untitled for your disk, great imagination there.