How to promote Apps outside App Store?

[danni]

There is no better option than to use Twitter Ads, Facebook Ads, and Linkedin Ads.
Please using these social media platforms will get to know about your mobile app, and they may install your app!

For Local or regional courier service Twitter ads and /or promotions are good. But I don't think that Linkedin Ads are much worth the spend.

Sure, yeah fb can also perform well if the campaigning done alright but rather than that fb is also not much effective if you don't have much followers base.

We don't even know that OP is looking for paid solutions.