Hi,
I think the MLAdapter has been replaced by LearningAgents. With this plugin you can train NPC behaviour through reinforcement learning.
There is a nice course on LearningAgents also telling you what it can do, you can find it here.
If you are looking how you can run a pretrained language model inside the engine, you can do so using the NeuralNetworkEngine (NNE).
There is also a course on the Epic Developer Community you can find here.
Just a warning upfront: Getting an LLM running is challenging, as you have to port the tokenizer of your model and implement the strategy how to pick the next tokenz (beam search, greedy, etc.).
I recommend that you start using the NNERuntimeORTCpu backend as it has the highest chance to be able to run your model.
I hope that helps as a starting point, good luck!