How do I get that "VHS" plugin?

Red Giant Universe has a VHS plug-in with a number of different settings and presets: Buy Red Giant Universe with VHS | Download the free trial

Universe is a subscription-based tool, which you can get monthly for $20 or yearly for $99. They also have an academic membership for $49.50/yr. You can't buy VHS from Red Giant on its own.

Best option is to actually transfer onto VHS and then record back in.

If you can't do that, look on Youtube - there are loads of tutorials on how to achieve this effect.