The language models required for an AI-based engine are huge and require over a few gigabates of space. We decided to exclude them from the default package and implement a mechanism of remote downloading if advanced proofreading is required. This is shown as a separate step in the installers where you can make your choice.
You must have the Internet connection enabled and have free space available on the disk according to Hardware requirements for v5.7.0+. If these criteria are met, the language models will be downloaded automatically.
Otherwise, the download will fail and you will have an option to download the models manually and enable them accordingly.
If you have trouble with the described steps, it's better to use the automated option when there is an Internet connection in place.