Step 6 has to process every page in your wiki. It will only process a small number of pages at a time (probably less than 50) because you server takes a long time to do this. It only processes pages until it detects the script is about to time out, then it reloads the page for a new batch. If you have several thousand wiki pages, this step might have 20 or more batches, but there is no fixed number, as it determines when to start a new batch based on a timer. Other sites, including ones I have tested personally, do finish this step, although most require several batches.
That is working as designed.
The error mentioned in your OP is in a file located here: dbtech/downloads/hooks/userdata_start.php. That is not a VaultWiki file. It looks like it's one of DBTech's mods.
Please report the issue to DBTech. The error in that file is:
Use of undefined constant TYPE_BOOLEAN - assumed 'TYPE_BOOLEAN'
The constant they probably intend to access is named TYPE_BOOL.