Please make sure you go to Settings > Reading. And set the ‘Posts page’ to be the one that you want your blog archive to appear on. Like ‘Blog’ in the following screenshot:
Also, if you’re not really fluent with WordPress themes, I highly recommend you follow the setup instructions in the User Guide and import the demo content. That should make figuring things out much easier. In case you don’t know where to find the User Guide:
Go to https://themeforest.net/downloads. Find the theme and click ‘Download’ > ‘All files & documentation’. Download and unpack the zip file. The User Guide will be in the ‘Documentation’ folder.