how do i get pages with high Sierra

If the user ( you) have Owned Pages previously open Apple Store and look in Previous Purchased or Owned Tab. You may need to scout this in more detail as it has been a long time since I have used the Apple Store in High Sierra.

If Pages appears as having been purchased or Owned - it should be available and compatible with High Sierra.

Should it not be available there are other free software like LibreOffice Just be sure to download a version compatible with High Sierra

Omitted on previous posting - previous Purchases or Owned are tied to the Apple ID used at time of Purchase.

Have the user used a different Apple ID at that time and subsequently changed to another Apple ID - the Previous Purchases will not appear in the Apple Store.

If you were using Time Machine on that High Sierra installation, just restore Pages from the /Applications folder on that backup using the /Applications Time Machine application.

Failing the first sentence, launch the Mac App Store and be signed in with the same Apple ID as you used to install Pages previously. Press the option key while clicking the Purchase tab, and Pages should appear there with an Update/Install button. Because the current (v11.2) Pages requires macOS Big Sur or later, the first dialog you receive will basically state you need to upgrade your Mac. Acknowledge (do not click Cancel) that dialog and a second dialog should appear offering to install the last compatible version (v8.1) of Pages for High Sierra.

If the preceding paragraphs do not result in restoring Pages to your Mac, your last recourse is to use Pages for iCloud in order to access existing or create new Pages documents. LibreOffice cannot open existing Pages v5 and later documents.

You can’t as the latest version is incompatible with High Sierra. If you ever purchased it in the past you might be allowed to download an old version.

Then do as Phillips said and look in Purchased in the App Store.