Clearly label the download button and mention the file size.
To help you create a "good post" for this topic, I need to know a bit more about what you're actually sharing. The phrase is very specific but can refer to a few different things depending on the community.
Could you clarify what is inside that zip file? For example: Is this a resource pack with resolution textures for version 1.25?
Mention that screenshots or a video preview are included/attached.
Is it a collection of 125 drum loops at 128 BPM? How to structure a great download post: