Convert existing website to Multisite w/Marketpress

We've gotten a little feedback but it seems a bit involved and we'd prefer not having this cause issues as we're running a bit behind schedule as it is! We're trying to keep it so the vendor pages are setup as sub-directories rather than sub-domains, and were told to install Snapshot Pro to transfer existing data using the full cloud backup feature, and the create a fresh install of Multisite; after the backup is completed, when they say "fresh install" would that in effect be wiping the entire site and starting from scratch, rebuilding it from the backup images?

Is there a tutorial available on best practices for converting an existing website (not an WPMUDEV theme or currently using any plugins) to Multisite w/Marketpress? If there is no tutorial on this process, is it possible to have it explained in detail in a support ticket or is there another place that we'd need to request this?

Additionally, when checking server support information saw the message below at the top of the page, any ideas what this might be in regards to or where to direct me?
Warning: mysqli_get_server_info() expects parameter 1 to be mysqli, resource given in /home/xxxxxxxxxx/xxxxxxxxx/xxxxxxxxxxx/wp-content/plugins/wpmudev-updates/template/support-system.php on line 77