Transfer Wordpress instance in a multisite environment


I need help with transferring a multisite instance from a competitor over to my server as an independent instance. I have created the database, imported the data in, but since the site relates to URL pointing to competitor multisite hosting, I can't certify if the website will work after turning over the DNS to my hosting server. Homepage displays most of the info right, but I get a 404 on the main image. I don't know if I have done all the necessary steps to modify the config files with the new links from my server.