Welcome to the community @noy! 
You can contact Patrick through the experts page! : Find Freelance Adalo Designers, Developers, & Agencies
Adalo docs : Filtering Airtable Lists | Adalo Resources
Useful thread : Filter (airtable populated) list by search term?
Similar video made by me : Airtable Names start with a letter.mp4 - Google Drive
You can store the category name in a input or in a user property and filter the sub-list with that input or property but let me ask you this, how you built your db on airtable? Some screenshots or a video?