You can't do that within a table. Tables do not cater for automatic flow of content to the next column.
In my previous attachment I showed you how to do it with a section break and a column setting in the new section. I'm attaching another document that looks like your layout. The black table header is a table, then follows a normal paragraph in one column layout.
After that, a section break starts for a three-column section. Add new entries at the end of the third column and the section will grow, distributing the content evenly across the three columns.
After another section break, we're back to single column. Then, a section break and a two-column layout. Finally, a section break and back to single column.
The gray area on the left is a text box.
Turn on paragraph marks to see the breaks, etc.
cheers, teylyn