Welcome to the forum @Koushiky !
We love the work you are doing at Climate Asia. I would recommend having conversations with your key stakeholders - in this case trainers, trainees/participants, other service providers to understand what their needs would be like and then we can recommend you the right tools. Usually training is more of a course/structure challenge than a tech challenge.
Once we understand the needs, we will be able to recommend Free & Open Source Tools that might be best fit for your users. I will coordinate with you to do some of the interviews with the stakeholders and also guide you through the same. Looking forward to it.
In the meantime these following threads are a good read