You got a few things wrong.

1. zappl does allow tags we just have a more advanced method of detection so we allow users to set them in posts. like #tag the post then auto detects that.
2. Zappl allows the use of unlimited tags in your posts as long as you don'y go over the character limit.
3. Your main feed isn't going to load because no one that you follow is posting on zappl. Most posts default to the key zappl so search zappl in the search box.
4. The main feeds for new hot trending and so on they do work its just the lack of users posting makes them not load.
5. Zappl only loads zappl content and uses app filtering to block out any content not made on zappl.

Also Last point its not called steemit blockchain its the steem block chain So your title should be steem on smart phone.

Zappl guide: https://steemit.com/zappl/@zappl/guide-how-to-use-zappl-com