True, But the problem with that is if you do it on for example TOPS (from example data) it will return 0, while there are 50 items, and also this will return all items (their colors and everything)

No problem, i edited question i was at fault. I taught it was somehow possible. i do get the ID, and search by that ID , but the problem is getting all product details as i get only sku

But this will return me Products with name like Leggings, I need Products by Category ID or Category Name which i get from myshop.com/rest/V1/categories/21/products . Yes i know but that will return me Products SKU, and i need all product data

I solved this by "reinstalling" magento, fresh install and now it worked. The funny part is i didn't do anything different than the first time.

can you give me details on your server configuration (Php version, Database...). So i can compare to mine, i am wondering why it is working now (since i have no clue to why it is working now on version 2.2.2 )?

I was able to get it working with new a installation. Really strange, didn't do nothing different than before with version 2.2.2.

I will be building an mobile app, so that is the reason i chose this way. I will try this too. Just to see if i can get the user info and not the error

My version is 2.2.2

I tried exactly this before and i was getting the same error in browser. So there must be an error somewhere else?

I created this customer and i am using his data to get customer token ( If i figured out correctly ) then to get his data. I didn't add / change any roles, as i taught it was not necessary ( Since documentations didn't mention to do that for Customer access tokens, only for Integration token type)