Your website is returning 500 error message and you can read the following in the php-errors log file
Error: Class 'Drupal\search_api\Entity\Index' not found in /mnt/www/html/***/docroot/modules/contrib/search_api/search_api.views.inc on line 43
The Search API (search_api) module contains an
Index.php file (with a capital
i) in the
... and this file is actually not present in the codebase on Acquia Cloud.
This might be due to the fact that by default, Mac OS uses a case insensitive file system. This can lead to issues for Drupal developers when a filename changes case in a module or core release. To mitigate this, Acquia recommends adding a global config to force git to pay attention to the case in filenames. You can do this by running the following from a command line:
git config --global core.ignorecase false
If the issue persists after making this change, you might want to contact Acquia Support.