Car Accessories Cart system with roadside assistance

I have setup an Opencart system and bought a plugin from "knowband" that could easily pack the web into app with better categorize.  The current problem is
1. Registration is not working after added Custom fields.

I added 3 custom fields at Opencart which allow user to select Car Made, write Model and Number plate upon registration, but registration is not working when custom field is added.

2. I have created an "auto-fill" shipping address from Geolocation and i need to "post" the data from what we get from "auto-fill" into Opencart database.

3. I need a new homepage for the mobile version which enrich user's experiences (i have the design and link)

4. Knowband's plugin included the "Push" function from google firebase . I need a page that simply shows pass notification (history) that user can interact with.


5. I need additional database for user's vehicle record (some people have more than 1 car)