error while tryng to enable the modue

Problem/Motivation

Fatal error: Declaration of Drupal\crowdfunding\FormControllers\PledgeSelection::build() must be compatible with Drupal\cool\Controllers\FormController::build($form, &$form_state) in /home/dev2/web/public_html/sites/all/modules/crowdfunding/src/FormControllers/PledgeSelection.php on line 5

Steps to reproduce

error while trying to enable the module

PHP 7