Why cannot I install this module?
If you go through the panels module README file. It clearly says the below:

dependencies:
  - ctools
  - layout_discovery
  - drupal:system (&gt;= 8.3.x)
test_dependencies:
  - page_manager


Make sure you have the above modules pre-installed for Panels.

For further help you can follow here: https://www.ostraining.com/blog/drupal/panels-drupal-8/

Else, revert back for further help.