Text Columns in Tab

the tab content is set up like any other content that makes up part of a post or page. Try installing a plugin that provides columns via shortcodes and use that to set up the columns & column content where you would normally put any other tab content

Most themes now include short-codes for columns since bootstrap had a huge impact on web design.

I use my theme’s short-codes for columns in the tabs. Just be careful how many columns you use inside a tab, the space is smaller depending on the theme and layout of the page.