The good news is that; several third-party tools let you mobile no database schedule your Facebook group posts. Here are some of them;
1. Hootsuite
Hootsuite allows you to manage your Facebook groups easily. When you sign into the Hootsuite dashboard, you can schedule posts, share videos, engage with followers, and measure the impact of your efforts—all from that single platform.
2. Buffer
Buffer also allows you to schedule your Facebook group posts. However, it requires you to connect your Facebook group by authenticating your Facebook profile with an admin role before you can do so.

3. Sprout Social
Sprout Social lets you post on your Facebook group. And just like Buffer, it will need you to connect through your Facebook profile.
4. Edgar
Edgar also requires the same as Social Sprout.
Ultimately, the answer to the question, “Is there a tool to schedule posts on Facebook groups?” is YES, there is.