Bro a correction to earlier, Databse is not limited to DB connectivity, it can also include text files/log etc.
I think you are correct here but also keep in mind that it is upto you which Tier your Application ends up in. So by the end of development, it could have evolved to tier 3 if you want.
You are developing the architecture so just keep a specific Tier in your mind that fits your application.
Tier 3 is the standard these days. The problem with thinking about IDM as a Tier 2 is that we don't really know how it works. Only the developer can answer this question. In your case, you are trying to make an IDM like Download Manager but since you are developing it, you should know better of its Tier instead of thinking of IDM.
Maybe IDM has some sort of integration with its Database, like there is some feature which uses it heavily. It is not just a simple download manager after all. So we can't really put it into a specified tier.
So my advice to you is to stop focusing on the Tier of IDM and just focus on your application and its Tier.
Yes, i am although not really developing/working on anything right now.
As for the answer to your question, no, it is not a tier 3 application. There is no interaction with DB involved here. Similarly, IDM is not a Tier 3 application. Hope that answers your question.