This article is relevant to users on all plans.
Because Coassemble is a global product, we use inbuilt browser support for checking spelling mistakes. This way, the spelling suggestions adapt to the end-users settings. To access suggestions you just need to right-click on the word with the red line through it. If you're on a mac, it's command right click.
Another suggestion is to install the free Grammarly plugin for your browser. Our team here uses it and they think it's great!