You might be trying to install a version older than the one currently on your phone. Delete the old version first.
If you are overwriting an existing version, back up your app data.
Trashbox is a popular third-party repository for Android apps. Users often turn to it when: Their device lacks pre-installed Google services. They need a specific older version of the Store. The official app was accidentally deleted. Step-by-Step Installation Guide 1. Enable Unknown Sources