Dialog to make user accept custom EULA in unity asset store package before downloading it.

We are developing a product that we want to upload to asset store.

We want the developer to accept the EULA before downloading the product.

Is there a way in which I can display some kind of EULA dialog that the user has to accept before the asset is downloaded?

No, you can’t. From the Asset store EULA:

“Any Asset that you acquire from the Unity Asset Store that has been developed by Unity or that has been made available by third-parties (“Providers”) that are not affiliated with Unity, will be subject to Unity’s standard Unity Asset Store End User License Agreement (“Unity-EULA”)”