Can't install MongoDB docker on raspberry
This means that the container that you are trying to pull is not available for the architecture, in this case it would be linux/arm64. Maybe there is an image available now. I would search for 'docker mongodb arm64' to see. I see support for mongodb under arm64v8 architecture, which would be in Raspberry Pi 4. Maybe you want to upgrade, as your chip is arm64v7.

This issue explains error message in a bit more detail.

Answers under this issue are going to help you run MongoDB under ARM64.