So the default for map ports is 8888. If these are not mapped to localhost, you will not be able to process the page request. Most likely, your local host points to port 80. To fix this, open MAMP, go to preferences, ports and click the Set Web & MSQL ports to 80 & 3306.
Your default MAMP tool/ PHP Admin will not work, so you’ll have to go to it directly http://localhost/phpMyAdmin.
Once you do this your page will load.
You may want to use the Search-Replace-DB-master tool to update links if you imported an existing WordPress site. Remember that the username is root and password is root for local defaults.